Question 2 :
If $\displaystyle { R }_{ 1 }$ and $\displaystyle { R }_{ 2 }$ are respectively the filament resistance of a 200 watt bulb and 100 watt bulb designed to operate on the same voltage then.
Question 3 :
An electrical device operate at 12 A current and 120 V D.C . If it is connected with 250 V and 30 Hz AC. then power consumption:
Question 4 :
A resistor of resistance $R$ is connected to an ideal battery. If the value of $R$ is decreased, the power dissipated in the resistor will
Question 6 :
A dynamo develops $0.5 A$ at $6 V$. The energy which is generated in one second is
Question 7 :
If the current passing through an electric bell is doubled, the heat produced will become
Question 8 :
An electric iron is connected to the 230 V mains <span>supply. A current of 8 A flows through the iron. How much energy is transferred to the heater each </span>second?
Question 9 :
What happens to the power dissipated in the resistor when the resistance is quadrupled and the voltage remains constant?<br>
Question 10 :
The resistance of a conductor is reduced to half its initial value keeping voltage applied constant. In doing so the heating effects in the conductor will become <br>
Question 11 :
Which among the following is the commercial unit of electric power?
Question 13 :
An electricity bulb of 100 watt is connected to supply of electricity of 220V. Resistance of filament is
Question 14 :
A bulb of $\displaystyle 22\Omega $ is producing light when connected to 220V supply. What is the electric power of the bulb.
Question 15 :
$\displaystyle P=\frac { { V }^{ 2 } }{ R } $ is applied when
Question 17 :
You are given three bulbs 25 W, 40 W and 60 W . Which of them has the lowest resistance?
Question 18 :
An electric heater has resistance 150 ohms and can bear a maximum current of 1 ampere. If the heater is to be used on 220 volt mains, the <span>least </span>resistance required in the circuit will be
Question 19 :
You are given a resistance wire of length 50 cm and a battery of negligible resistance. In which of the following cases is largest amount of heat generated?
Question 20 :
Amount of electric energy consumed in a circuit per unit time is.
Question 21 :
Calculate the current through a lamp of 25w operating at 220v.
Question 22 :
In a house, individual powers of two elements are $<span>100\ W\ 100\ W</span>$. The effective power of their series combination will be :
Question 23 :
<span>For a heater rated at 4.4 kW; 220 V . Calculate the current drawn by the heater.</span>
Question 24 :
The power dissipated in a conductor of resistivity $\rho$ is proportional to
Question 25 :
Two wires $A$ and $B$ of same material and mass have their lengths in the ratio $1 : 2$. On connecting them to the same source, the rate of heat dissipation in $B$ is found to be $5 W$. The rate of heat $B$ dissipation in $A$, is
Question 26 : The table below show the resistance values for three different resistors and the currents through each resistor. What is the ranking order of the power dissipated by each resistor, greatest first.<table class="wysiwyg-table"><tbody><tr><td>Current 1</td><td>2I</td></tr><tr><td>Resistance 1</td><td>R</td></tr><tr><td>Current 2</td><td>I</td></tr><tr><td>Resistance 2</td><td>2R</td></tr><tr><td>Current 3</td><td>I</td></tr><tr><td>Resistance 3</td><td>4R</td></tr></tbody></table>
Question 28 :
What is the power produced by an appliance marked " $240 V$, $2 A?$
Question 29 :
In 5s, a charge of 25C leaves a battery, and 100 J of energy are delivered to an outside circuit. What is the potential difference across the battery?
Question 30 :
A 60 watt bulb carries a current of 5A . Find the total charge passing through it in 1 hour.
Question 32 :
A room has AC run hours a day at a voltage of $220$V. The wirng of the room consists of Cu of $1$mm radius and a length of $10$m. Power consumption per day is $10$ commercial units . The fraction of it goes in the joule heating in wires is: $\rho_{cu}=1.7\times10^{-8}\Omega m$
Question 36 :
Relation between the power (P) consumed by a device, its resistance (R) and voltage (V) across it.
Question 38 :
What is the effective resistance of an appliance marked "240 V, 4 A'?
Question 39 :
A piece of copper wire connected to a 15 V battery produces heat energy at a rate of 100 W. This wire is replaced with the wire of the same material and gauge but double the length of the original wire.<br><span>How much heat will this new wire produce after 1 minute of operation?</span>
Question 40 :
An amount of electrical energy consumed in a circuit per unit time is
Question 42 :
Calculate the power of a source if it produces an energy of 250 joules in 10 sec.
Question 43 :
Resistance of a conductor is reduced to half its initial value, then heat generated in the conductor will become
Question 44 :
In the previous problem, the power lost in the cable during transmission is
Question 45 :
When a 1 ohm resistor is connected across the potential difference of 20 V, what will be power dissipation in it?
Question 47 :
Electric power is transmitted over long distance through conducting wires of very high voltage, because.
Question 50 :
When the current and voltage of an electric circuit is given. Then power can be calculated by:<br/>
Question 51 :
The coil of a heater is cut into two equal halves and only one of them is used in the heater.Then ratio of the heat produced by this half of the coil to that produced by the original coil is <br>
Question 52 :
Two filaments of same length are connected first in series and then in parallel. For the same amount of main current flowing the ratio of the (parallel to series) heat produced is
Question 53 :
A cable of resistance $10\, \Omega$ carries electric power from a generator producing $250 kW$ at $10,000 V$. The current in the cable is
Question 54 :
If $R_1$ and $R_2$ are the filament resistances of a 200 W bulb and a 100 W bulb respectively designed to operate on the same voltage, then
Question 55 :
Two cities are 150 km apart. Electric power is sent from one city to another city through copper wires. The fall of potential per km is 8 volt and the average resistance per km is $0.5\Omega$. The power loss in the wire is
Question 56 :
Two heating wire of equal length are first connected in series and then in parallel to a constant voltage source. The rate of heat produced in two cases is (parallel to series)
Question 57 :
Three equal resistors connected in series across a source emf together dissipate 10 watt. If the same resistors are connected in parallel across the same emf the power dissipate will be<br/>
Question 58 :
Two conductors of resistance 2 R and R are connected in series in a battery circuit. The ration of heats developed in them is :
Question 59 :
Which of the following quantities do not change when a resistor connected to a battery is heated due to the current?
Question 60 :
An element with emf $\varepsilon$ and internal resistance r is connected across an external resistance R. The maximum power is external circuit is 9 W. The current flowing through the circuit in these conditions is 3 A. Then which of the following is/are correct?
Question 61 :
The internal resistance of a primary cell is 4 $\Omega$. It generates a current of 0.2 A in an external resistance of 21$\Omega$. The rate of chemical energy consumed in providing the current is
Question 62 :
Two 220 volt, 100 watt bulbs are connected first in series and then in parallel. Each time the combination is connected to a 220 volt a.c.supply line. The power drawn by the combination in each case respectively will be
Question 63 :
If i is the current flowing through a conductor of resistance R for time t, then the heat produced (Q) is given by .....
Question 64 :
If $R_1$ and $R_2$ are the filament resistances of a $200 W$ bulb and a $100 W$ bulb respectively designed to operate on the same voltage, then:
Question 65 :
A current is divided into two resistors connected in parallel according to Kirchhoff's law, then the heat produced in the combination is
Question 66 :
Two electric lamps each of 100 watts 220 V are connected in series to a supply of 220 volts. The power consumed would be -
Question 67 :
Two electrical appliances are connected in parallel to a constant voltage supply. If the current in one appliance is $1\%$ less than that in the second appliance, then the power of the first appliance will be less by
Question 68 :
A transformer with turns ratio $\dfrac{N_1}{N_2}=\dfrac{50}{1}$ is connected to a $120$ volt AC supply. If primary and secondary circuit resistance are $1.5k\Omega$ and $1\Omega$ respectively then find out power out put.
Question 69 :
When a current I flows through a resistance R for time t, the electrical energy spent is given by
Question 70 :
An electric bulb is rated $220 V$ and $100 W$ . When it is operated om $110 V$,the power consumed will be-
Question 71 :
An electric bulb marked $40W-220V$ is connected with an electric supply of $110v$. Its elctric power is
Question 72 :
A short-circuited coil is placed in a time-varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns was to be quadrupled and the wire radius halved, the electric power dissipated would be<br>
Question 73 :
Calculate the power of an electric bulb which consumes 2400 J in a minute
Question 74 :
An electric bulb is designed to draw power $P_{0}$ at voltage $V_{0}$. If the voltage is V, it draws a power P, then-<br>
Question 75 :
Two resistors when connected in parallel across a cell of negligible internal resistance use fourtimes the power that they would use when connected in series across the same cell. If one of the resistors has a resistance of 10$\Omega $ the resistance of the other is<br/>
Question 76 :
Calculate the resistance of the bulb when a 60-watt light bulb operates at a voltage of 120 V.<br/>
Question 77 :
You are given a resistance wire of length 100 cm and a battery of negligible internal resistance. In which of the following cases is the largest amount of heat generated?
Question 78 :
If a 2 kW boiler is used everyday for hour, then electrical energy consumed by boiler in thirty days is
Question 79 :
The electrical energy consumed by a $30\ W$ bulb in $5$ minutes is ______.
Question 80 :
Electric room which operates at 225 volts has resistance of 50 ohms. Power of the radiator is approximately
Question 81 :
A constant voltage is applied between the two ends of a uniform metallic wire. If both the length and radius of wire are doubled, then :
Question 82 :
Three equal resistors connected across a source of e.m.f. together dissipate 10 watt of power. What will be the power dissipated in watt if the same resistor are connected in parallel across the same source of e.m.f.?
Question 83 :
An electric iron is connected to a $200 V$ mains supply and draws a current of $4.0 A$ What is the power rating of the iron ?<br/>
Question 84 :
Three equal resistors connected across a source of e.m.f. together dissipate 10 watt of power. What will be the power dissipated in watts if the same resistors are connected in parallel across the same source of e.m.f ?
Question 85 :
The same mass of copper is drawn into two wires 1mm and 2mm thick. Two wires are connected in series and current is passed through them. Heat produced in the wires is in the ratio
Question 86 :
If current in an electric bulb change by $1$%, then the power will change by
Question 87 :
The electric power is supplied through the copper wires from a one city to another city which is 150 km apart. If the terminal voltage and average resistance of per kilometer are 8 volt and 0.5 $\Omega$ respectively then the power loss in a wire is :
Question 88 :
The supply voltage to a room is $120\ V$. The resistance of the lead wires is $6\ \Omega$. A $60$ $W$ bulb is already switched on. What is the decrease of voltage across the bulb, when a $240\ W$ heater is switched on in parallel to the bulb?
Question 89 :
An electric iron of heating element of resistance $88 \Omega$ is used at $220$ volt for $2$ hours. The electric energy spent, in unit, will be:
Question 90 :
A wire when connected to 220 V mains supply has power dissipation $P_1$. Now, the wire is cut into two equal pieces, which are connected in parallel to the same supply. Power dissipation in this case is $P_2$. Then $P_2\,:\,P_1$ is
Question 91 :
The rating of an electrical appliance is $60 W$, $220 V$. What is the safe limit of current in it, while in use ?
Question 92 :
Three identical bulbs are connected in parallel with a battery. The current drawn from the battery is 6 A. If one of the bulbs gets fused, what will be the total current drawn from the battery ?
Question 93 :
In an electric heater 4 amp current passes for 1 minute at potential difference of 250 volt, the power of heater and energy consumed will be respectively
Question 94 :
When a voltage of 20 volt is applied between the two ends of a coil, 800 cal/s heat is produced. The value of resistance of the coil is :-<span><br></span>
Question 96 :
Electric power is transmitted over long distances through conducting wires at high voltage because
Question 98 :
An electric iron draws a current of $15 A$ from a $220 V$ supply. What is the cost of using iron for $30$ min everybody for $15$ days if the cost of unit is 2 rupees?$ (1\ unit =1 \ k Wh)$
Question 99 :
If a bulb of 60 W is connected across a source of 220 V, the current drawn by it is:
Question 100 :
Electrical power P is given by the expression P = $\dfrac{Q \times V}{t}$. time. What does $Q$ and $V$ stand for?
Question 101 :
You are given $5 m$ length of heating wire, it has resistance of $24 \Omega$. It is cut into two and connected to $110$ volt line individually. The total power for the two half lengths is:
Question 102 :
When two unknown resistors are connected in series with a battery, $225 W$ power is delivered to the combination with a total current $5A$. For the same total current $50W$ is delivered when the resistors are connected in parallel. Find the ratio of the two resistances.
Question 103 :
Heat is produced at a rate given by $H$ in a resistor when it is connected across a supply of voltage $V$. If now the resistance of the resistor is doubled and the supply voltage is made $V/3$, then the rate of production of heat in the resistor will be
Question 104 :
A battery of emf $'E'$ and internal resistance $'r'$ is connected to a resistor of resistance '$\displaystyle { r }_{ 1 }$' and $Q$ joules of heat is produced in a certain time $'t'$. When the same battery is connected to another resistor of resistance '$\displaystyle { r }_{ 2 }$', the same quantity of heat is produced in the same time $'t'$. Then , the value of $'r'$ is:
Question 105 :
N lamps each of resistance r, are fed by a machine of resistance R. If light emitted by any lamp is proportional to the square of the heat produced, prove that the most efficient way of arranging them is to place them in parallel arcs, each containing n lamps, where n is the integer nearest to.
Question 106 :
A dynamo develops $0.5 A$ at $6 V$, the power delivered is ______.
