Question 1 :
The heating element in an electric iron is made up of :
Question 2 :
In our houses all electrical devices operate on 220 V. It implies that
Question 3 :
Two resistors are connected a) in series b) in parallel.<br>The equivalent resistance in two cases are $9\ ohm$ and $2\ ohm$ respectively. Then the resistance of the component resistors are.
Question 4 :
If five equal pieces of $25\Omega$ are connected in parallel, then their equivalent resistance will be............
Question 6 :
Two wires of Aluminium have same weight and have lengths of 10m and 20m. Their resistances are in the ratio.<br/>
Question 7 :
We have n resistors each of resistance R. The ratio of the combination for maximum and minimum values is
Question 8 :
Which of the following will produce maximum wastage of electricity ?
Question 9 :
The temperature of a conductor is increased. The product of resistivity and conductivity:<br/>
Question 10 :
Mark the correctreason/s why nichrome is used for making heating element of electricalappliances.
Question 11 :
A constant voltage is applied between the two ends of uniform metallic wire, some heat is developed in it. If both the length and the radius of the wire halved, the heat developed in the same duration will become
Question 12 :
From below which are the applications of heating effect of electric current?<br>
Question 14 :
The thermo-emf of a copper-constant couple is $40\muV$ per degree. The smallest temperature difference that can be detected with this couple and galvanometer of $100\Omega$ resistance capableof measuring the minimum current of $1\mu A$ is
Question 15 :
A resistor connected to a battery is heated due to current through it. Which of the following quantity does not vary?<br>
Question 16 :
A current $i$ passes through a wire of length $L$, radius $R$ and resistively $\rho$. The rate of heat generated is
Question 17 :
For a heater rated at4.4 kW; 220 V . Calculate the energy consumed by the heater in 4 hours?
Question 18 :
The emf of the battery in a thermocouple is doubled. The rate of heat generation at one of the junctions will 
Question 19 :
The resistance of the series combination of two resistances is S. When they are joined in parallel the total resistance is P. If S = nP, then the minimumpossible value of n is
Question 20 :
Shivam went for buying a CFL from D-mart, what safety mark he should look for?
Question 21 :
As the temperature of a conductor increases, its resistivity and conductivity change. The ratio of resistivity to conductivity<br>
Question 22 :
Constantan wire is used for making standard resistance, because it has
Question 24 :
Two resistors of resistance $\displaystyle { R }_{ 1 }$ and$\displaystyle { R }_{ 2 }$ having$\displaystyle { R }_{ 1 }>{ R }_{ 2 }$ are connected in parallel. For equivalent resistance R, the correct statement is
Question 26 :
The smallest resistance that can be obtained by combining 10 resistors each of resistance $10 \Omega$is
Question 27 :
The neutral temperature of a thermocouple is 275$^oC$ and the temperature of inversion is 600$^oC$. The temperature of the cold junction is
Question 29 :
Identify the changes in a circuit on adding a light bulb in parallel to the actual resistance of the circuit. It will:<br/>
Question 30 :
Which is the equivalent resistance when resistors $3 \Omega$ and $6 \Omega$ are in parallel?<br>
Question 31 :
When the electric resistance are connected in parallel, which one of the following quantities is not affected ?
Question 32 :
What is the total resistance when four resistors of $20, 40, 60$, and $80$ respectively are connected in parallel (in ohm)?
Question 34 :
Why are bulbs filled with chemically inactive Nitrogen or Argon gas?<br>
Question 35 :
The cells are joined in parallel to get the maximum current when
Question 36 :
An electric bulb of $30\ W$ consumes $0.72$ units of energy in a day. Find the number of hours it is working in a day?
Question 37 :
A typical thermistor can easily measure a change in temperature of the order of
Question 38 :
The smallest resistance that can be obtained by the combination of  $n$ resistors, each of resistance  $R$ is:
Question 39 :
How much units of energy is consumed in operating ten 50 watt bulbs for 10 hours per day in a month (30 days)
Question 40 :
When a metallic conductor is heated then the atoms in the metal vibrate with ?<br/>
Question 41 :
A piece of copper and another of germanium are cooled from room temperature to 80K. The resistance of
Question 42 :
You have the following appliances each of $500\ W$ running on  $220\ V$ a.c.: (1) Electric iron.(2) Electric lamp. (3) Electric room heater. The electric resistance is:
Question 45 :
A 24V potential difference is applied across a parallel combination of four 6 ohm resistor. The current in each resistor is:<br/>
Question 47 :
Which of the following quantities do not change when a resistor connected to a battery is heated due to the current?<br>
Question 48 :
Why is electric power transmitted over long distances at high voltage?<br>
Question 49 :
Calculate the energy consumed by $2\ kW$ heater used for $1\ hr$ every day in a period of $30\ \text{days}$.
Question 50 :
Mark the correctreason why tungsten is used for making filament of electric lamp.
Question 51 :
An electron with an initial speed of $4.0\times 10^6ms^{-1}$ is brought to rest by an electric field. The mass and charge of an electron are $9\times 10^{-31}$kg and $1.6\times 10^{-19}$C, respectively. Identify the correct statement.<br>
Question 52 :
A table lamp of power 60 W consumed 9 (commercial) units of electricity in the month of April. For how many hours per day, on an average, was the lamp in use?
Question 53 :
Four wires made of same material have different lengths and radii. The wire having more resistance in the following is<br/>
Question 54 :
Two charged spheres of radii $R_1$ and $R_2$ have equal surface charge density. The ratio of their potential at an equidistantexternal point is
Question 55 :
 The equivalent resistance R of three resistors $R_1$, $R_2$ and $R_3$ joined in parallel is
Question 56 :
Assertion: Heater wire must have high resistance than connecting wires and high metallic point
Reason: If resistance is high the electrical conductivity will be less.
Question 57 :
The amount of work done in joules, when one unit electric charge moves from one point to another point in an electric circuit is called: 
Question 58 :
If the area of a material is $4 m^2$ and length $20 m$. What will be the resistivity of that material when its resistance is $10 \Omega$?
Question 59 :
A particle with acharge of 3 coulombs is taken from a point at a potential of 50 V to anotherpoint at a potential of 120 V. Calculate the work done.
Question 60 :
The resistance of an iron wire is $10\Omega$ and its temperature coefficient of resistance is $5\times 10^{-3}/^oC$. A current of 30 mA is flowing in it at $20^oC$. Keeping potential difference across its ends constant, if its temperature is increased to $120^oC$ then the current flowing in the wire will be (in mA)<br>
Question 61 :
The resistance of a carbon filament at $0^oC$ is 104$\Omega$. It is connected in series with an iron wire. The temperature coefficients of resistivity of carbon and iron are $- 0.0003$ and $0.0052$ per $^oC$ respectively. What must be the resistance of iron wire so that the combined resistance does not change with temperature?
Question 62 :
A lamp of $100\ W$ and a heater of $1\ kW$ are in simultaneous use for $10\ hrs$. The units of electricity consumed according to the meter in the house is:<br/>
Question 63 :
A wire of uniform thickness with a resistance of $27\, \Omega$ is cut into three equal pieces and they are joined in parallel. The equivalent resistance of the parallel combination will be :
Question 64 :
A wire has a resistance of 10 ohm. Its resistance if it is stretched by one-tenth of its original length is:<br/>
Question 65 :
The resistance of hot tungesten filament is about 10 times the cold resistance. The resistance of 100 W and 200 V lamp, when not in use is
Question 66 :
$10$ wires (same length, same area, same material) are connected in parallel and each has $1\Omega$ resistance, then the equivalent resistancewill be
Question 67 :
Two wires have their lengths in the ratio $1 : 3$ diameters in the ratio $2 : 3$ and their materials have specific resistances in the ratio $2 : 1$. Then the ratio of their resistances is :<br/>
Question 68 :
The potential at a point due to a charge of $5\times { 10 }^{ -7 }C$ located $10cm$ away is  $4.5\times { 10 }^{ 4 }V$. The work done in bringing a charge of $4\times { 10 }^{ -9 }C$ from infinity to that point is:
Question 69 :
At what temperature will the resistance of a copper wire become three times its value at $0^{\circ}C$[Temperature coefficient of resistance for copper $=4\times 10^{-3}per^{\circ}C$] :-<br>
Question 71 :
Copper and silicon is cooled from 300 K to 60 K, the specific resistance :-
Question 72 :
If a charge is moving along the direction of coulomb's force of an electric field,
Question 73 :
Two wires of the same dimensions but resistivities $\rho_{1}$ and $\rho_{2}$ are connected in series. The equivalent resistivity of the combination is
Question 74 :
The lowest resistance which can be obtained by connecting $10$ resistors each of $1/10\ ohm$ is
Question 75 :
A constant voltage is applied between the two ends of a uniform metallic wire due to which some heat is developed in it. The heat developed is doubled if:<br/>
Question 76 :
The resistance of a wire is 5 ohm at $50^{\circ}$C and 6ohm at $100^{\circ}$C. The resistance of the wire at $0^{\circ}$Cwill be:<br>
Question 77 :
A uniform length of wire $1.2$ m has a resistance of $16\Omega$. It is stretched such that its resistance is $36\Omega$. The new length is<br/>
Question 78 :
Wires A and B have resistivities $\rho_A$ and $\rho_B$, $(\rho_B =2\rho_A)$ and have lengths $l_A$ and $l_B$. If the diameter of the wire B is twice that of A and the two wires have same resistance, then $\displaystyle\frac{l_B}{l_A}$ is:<br/>
Question 79 :
The resistance of a coil in a platinum resistance thermometer at $0^{\circ}C$ is 5 ohm and at $100^{\circ}C$ it is 5.75 ohm. Its resistance at an unknown temperature is 5.15 ohm. Then the unknowntemperature will be :-<br>
Question 80 :
An electric heater operating at $220\ V$ boils $5\ l$of water in $5\ min$. If it is used on $110\ V$,it will boil the same amount of water in:<br>
Question 81 :
The temperature coefficient of resistance of conductor varies as $\alpha (T)=3T^2+2T$. If $R_0$ is resistance at $T = 0$ and $R$ is resistance at $T$, then<br>
Question 82 :
When a current is passed in a conductor, $3^oC$ rise in temperature is observed. If the strength of current is made thrice, then rise in temperature will approximately be:
Question 83 :
Two rods of same material and length have their electric resistance in ratio $1:2$. When both rods are dipped in water, the correct statement will be
Question 84 :
Calculate the total power of 2 fans, if each of them draws a current of $5 A$ at a p.d of $200 V$.
Question 85 :
The resistance of a wire is 10 ohm. The resistance of a wire whose length is twice and the radius is half, if it is made of same material is
Question 86 :
A $100W, 200V$ bulb is connected to a $160V$ supply. The actual power consumption would be<br/>
Question 87 :
A wire of length $L$ and 3 identical cells of negligible internal resistances are connected in series. Due to the current, the temperature of the wire is raised at $\triangle T$ in time $t$. $N$ number of similar cells is now connected in series with a wire of the same material and cross-section but of length $2L$. The temperature of the wire is raised by the same amount $\triangle T$ in the same time $t$. The value of $N$ is:
Question 88 :
A block of carbon, 1$.0 cm$ by $2.0 cm$ by $5.0 cm$, has a resistance of $0.015$ between its two smaller faces. What is the resistivity of carbon?
Question 89 :
On moving a charge of 20 coulombs by 2 cm, 2 J of work is done, then the potential difference between the points is:
Question 90 :
In a non-linear electric field, a charged particle returns to its initial point sometime after it is released in the field. The work done by the field is given by
Question 91 :
10 J of work is done in moving $\displaystyle 12.5\times { 10 }^{ 18 }$ electrons from one end to other end of a conductor. What is the potential difference between the two ends of conductor?
Question 92 :
Constanton wire is used in making standard resistances, because its :-
Question 93 :
The resistance of a wire at room temperature $30^oC$ is found to be $10\Omega$. Now to increase the resistance by 10%, the temperature of the wire must be: [The temperature coefficient of resistance of the material of the wire is 0.002 per $^oC$]
Question 94 :
Two wires of same material and same length have their resistances in the ratio 5 : 7. The ratio of the masses of the wires is<br/>
Question 95 :
Two wires of resistance $R_{1}$ and $R_{2}$ at $0^{o}C$ have temperature coefficient of resistance $\alpha _{1}$ and $\alpha _{2}$, respectively. These are joined in series. The effective temperature coefficientof resistance is :-
Question 96 :
A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be:
Question 97 :
The resistance of the series combination of two resistance is S. When they are joined in parallel through total resistance is P. If $S=nP$, then the minimum possible value of n is?
Question 98 :
If a copper wire is stretched to make it $0.1 \%$ longer, the $\% $change in the resistance is<br/>
Question 99 :
The ratio of lengths of two wires made up of same material is 2 : 3 and the ratio of areas of cross section 3 : 2 . The ratio of their resistances is<br/>
Question 100 :
The minimum resistance that can be obtainedby connecting 5 resistance of $\displaystyle \frac{1}{4} \Omega$ each is
Question 101 :
Two points P and Q are maintained at potentials of of $10V$ and $-4V$ respectively. The work done in moving $100$ electrons from P to Q is proportional to
Question 102 :
The resistance of an electrical toaster has a temperature dependence given by $R(T) = R_0 [1 + \alpha(T- T_0)]$ in its range of operation. At $T_0 = 300 K, R_0 =100 \Omega$ and at $T= 500 K, R= 120 \Omega$. The toaster is connected to a voltage source at 200 V and its temperature is raised at a constant rate from 300 to 500 K in 30 s. The total work done in raising the temperature is : 
Question 103 :
Given that $E = ((3x^2<br><br> + y) \hat i+ x \hat y) kV/m$,find the work done in moving a $- 2 \mu C$ charge from $(0, 5, 0)$ to $(2, -1 , 0)$ by taking the path:<br>$y=5-3x$
Question 105 :
A voltmeter and an ammeter are connected in series to an ideal cell of emf E. The voltmeter reading is V and the ammeter reading is l<br>
Question 106 :
The resistance of the series comb of two resistance is S. When they are joined in parallel the total resistance is P. If S=nP, then the minimum possible value of n is:
Question 107 :
A charge of $10$ C is brought from infinity to a point near a charged body and in this process, $200$ J of work is done.  Calculate the electric potential at that point near the charged body
Question 108 :
A square aluminium rod is 1 m long and 5 mm on edge. What must be the radius of another aluminiumrod whose length is 1 m and which has the same resistance as the previous rod ?
Question 109 :
Assertion: STATEMENT-1 : The current density $\vec{J}$ at any point in ohmic resistor is in direction of electric field $\vec{E}$ at that point.
Reason: STATEMENT-2 : A point charge when released from rest in a region having only electrostatic field always moves along electric lines of force.
Question 110 :
A point-charge of $6.0\times 10^{-8}$ C is situated at the coordinate origin. How much work will be done in taking an electron from the point $x=3$m to $x=6$m?
Question 111 :
The magnitude of electric field at different points along the length of the rod is given by
Question 113 :
How much work would be required to move a proton from the negative to the positive plate?
Question 114 :
An electric motor operating on $50 V$ D.C. supply draws a current of $10 A$. If the efficiency of the motor is $40\%$, then the resistance of the winding of the motor is:<br/>
Question 115 :
A potential difference of $2.5$V is applied across the faces of a germanium crystal plate. The face area of the crystal is $1$ $cm^2$ and its thickness is $1.0$ mm. The free electron concentration in germanium is $2\times 10^{19} m^{-3}$ and the electron and holes mobilities are $0.33 m^2/V$ and $0.17m^2/V$ respectively. The current across the plate will be?
Question 116 :
What should be the bill for the month of April for a heater of resistance 60.5 $\Omega$ connected 220 V mains, The cost of energy is Rs 2 per kWh and the heater is used for 3 hours daily?
Question 117 :
The length of a given cylindrical wire is increased by $100\%$. Due to the consequent decrease in diameter, the change in the resistance of the wire will be<br>
Question 119 :
A copper tube is of internal radius 4 mm and outer radius 5 mm. Its resistance is R$_{1}$. The tube is filled with a suitable copper wire. The resistance of the arrangement is R$_{2}$.Then R$_{2}$/R$_{1}$ is<br>
Question 120 :
The resistivity of the conductors is of the order of _______.
Question 121 :
A current of $I$ ampere flows through a resistance $R$ when connected across a cell of emf $E$ and internal resistance $1 \Omega$. When $R$ is increased by $50\%$, the current through the circuit is $0.8 A$. The value of $R$ is :
Question 122 :
Two electric bulbs rated ${P}_{1}$ and watt at $V$ volt are connected in series across $V$ volt mains, then their total power consumption $P$ is
Question 123 :
The materials in which the electrons are verytightly bound to the atoms, and are not free to flow -
Question 124 :
When $5V$ potential difference is applied across a wire length $0.1\m$, the drift speed of electron is 2.5 $\times 10^{-4} ms^{-1}$. If the electron density in the wire is 8 $\times 10^{28} m^{-3}$, the resistivity of the material is close to
Question 125 :
A number of condensers, each of capacitance $1\mu F$ and each one of which gets punctured if a potential difference just exceeding $500\ V$ is applied, are provided. An arrangement suitable for giving capacitance of $2\mu F$ across which $3000$ volt may be applied requires at least.
Question 126 :
Find the electric field in the copper wire of area of cross section $2\ mm^2$ carrying a current of $1\ A.$ The resistivity of copper is $1.7\times 10^{-8}\Omega m$.<br>
Question 127 :
An electric motor driven pump fills an overhead tank placed at a height of 20 m from the ground-level sump at a rate of 20,000 litre water per hour.The motor has an operating resistance of $22\Omega$ and is connected across a 220 V source.The efficiency of this motor is (Use$ g=9.8 m/s^2)$
Question 128 :
Two particles X and Y having equal charges, after being accelerated through the same potential difference , enter a region of uniform magnetic field and describe circular paths of radii $R_1$ and$R_2$ respectively. The ratio of the mass of X to the Y is
Question 130 : <p>Copper has one conduction electron per atom. Its density is $8.89{ g }/{ m^3}$ and its atomic mass is 63.54 g/mol. lf a copper wire of diameter 1.0 mm carries a current of 2.0 A. What is the drift speed of the electrons in the wire?</p>
Question 131 :
A material $\mathrm{B}$' has twice the specific resistance of $\mathrm{A}'$. A circular wire made of $\mathrm{B}$' has twice the diameter of a wire made of $\mathrm{A}'$. Then for the two wires to have the same resistance, the ratio $P_{\mathrm{A}}/P_{\mathrm{B}}$ of their respective lengths must be <br/>
Question 133 :
The displacement of charge $q$ in the electric field $\vec E = e_1\hat i + e_2 \hat j + e_3 \hat j$ is$\vec r = a \hat i + b \hat j$. The work done is
Question 134 :
Assertion: Ohm's law holds only for small currents in metallic wire not for high currents
Reason: For metallic wire resistance increases with decrease in temperature.
Question 135 :
The material in which the outermost electrons in the atoms are so loosely bound to their atoms that they are free to travel around are called _____________.
Question 136 :
A material $B$ has twice the specific resistance of $A$. A circular wire made of $B$ has twice the diameter of a wire made of $A$. Then for the two wires to have the same resistance, the ratio $l_{B} $ / $l_{A}$ of their respective lengths must be:
Question 137 :
An electric bulb is connected to a $20$ V battery of negligible internal resistance. The resistance offered by the bulb is $5$ $\Omega$. The electrical energy consumed by the bulb in $3$ hours is _____ kWh.
Question 138 :
Heater of an electric kettle is made of a wire of length L and diameter d. It takes 4 minutes to raise the temperature of 0.5 kg water by 40 K. This heater is replaced by a new heater having two wires of the same material, each of length L and diameter 2d. The way these wires are connected is given in the options. How much time in minutes will it take to raise the temperature of the same amount of water by 40 K?
Question 139 :
Heat flows radially outward through a spherical shell of outside radius$R_{2}$ and inner radius$R_{1}$. The temperature of inner surface is$\Theta _{1}$ and that outer is$\Theta _{2}$. At what radial distance fro m center of shell the temperature is just half way between$\Theta _{1}$ and$\Theta _{2}$
Question 140 :
Which of the following is the best conductor of electricity ?
