Heating Effect of Current

IMPORTANT

Heating Effect of Current: Overview

This topic covers concepts, such as, Electric Power, Heat Produced in an Electrical Resistance, Power Transmission, Power Supplied by a Battery, Power Consumed by a Battery & Maximum Power Theorem etc.

Important Questions on Heating Effect of Current

MEDIUM
IMPORTANT

In Circuit-1 and Circuit-2 shown in the figures, R1=1Ω,R2=2Ω and R3=3Ω.
P1 and P2 are the power dissipations in Circuit-1 and Circuit-2 when the switches S1 and S2 are in open conditions, respectively.
Q1 and Q2 are the power dissipations in Circuit-1 and Circuit-2 when the switches S1 and S2 are in closed conditions, respectively.

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Which of the following statement(s) is(are) correct?

MEDIUM
IMPORTANT

An electrical bulb rated 220 V,100 W, is connected in series with another bulb rated 220 V, 60 W. If the voltage across combination is 220 V, the power consumed by the 100 W bulb will be about _____ W.

EASY
IMPORTANT

Given below are two statements :
Statement I : A uniform wire of resistance 80 Ω is cut into four equal parts. These parts are now connected in parallel. The equivalent resistance of the combination will be 5 Ω.

Statement II : Two resistance 2R and 3R are connected in parallel in an electric circuit. The value of thermal energy developed in 3R and 2R will be in the ratio 3:2.

In the light of the above statements, choose the most appropriate answer from the options given below

MEDIUM
IMPORTANT

A direct current of 4 A and an alternating current of peak value 4 A flow through resistance of 3 Ω and 2 Ω respectively. The ratio of heat produced in the two resistances in same interval of time will be :

MEDIUM
IMPORTANT

A 220 V,50 Hz AC source is connected to a 25 V,5 W lamp and an additional resistance R in series (as shown in figure) to run the lamp at its peak brightness, then the value of R (in ohm) will be

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EASY
IMPORTANT

A resistor develops 300 J of thermal energy in 15 s, when a current of 2 A is passed through it. If the current increases to 3 A, the energy developed in 10 s is _____ J.

HARD
IMPORTANT

A conductor is made of an isotropic material (resistivity ρ ) has rectangular cross-section. Horizontal dimension of the rectangle decreases linearly from 2x at one end to x at the other end and vertical dimension increases from y to 2y as shown in figure. Length of the conductor along the axis is equal to l . A battery is connected across this conductor. Then:

HARD
IMPORTANT

Two long parallel conducting rails of zero resistance separated by a distance L are joined to a cell of emf E at one end. An external uniform magnetic field B is applied normal to the plane and into the plane of the rails as shown in the figure. A conducting bar of mass m and resistance R is placed across the rails. The bar can slide freely parallel to itself always remaining perpendicular to the rails.

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HARD
IMPORTANT

In the circuit shown in the figure R=50Ω,E1=253 volt and E2=256sinωt volt where ω=100πs-1. The switch is closed at t=00$ and remains closed for 14 minutes, then it is opened

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HARD
IMPORTANT

For the circuit show, all wires have negligible resistance, the battery has a constant internal resistance of r=8.0Ω and the two light bulbs B1 and B2 are identical, each with resistance Rbulb . The variable resistor is initially set R=26.0Ω. The switch S in the circuit now is closed. To what resistance must the variable resistor be set if bulb B1 is to have the same brightness after the switch is closed as it did with the switch open?

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MEDIUM
IMPORTANT

Two uncharged thin concentric spherical conducting shells 'A' and 'B' of radii R and 3R are connected through a resistance 'r' and switch 'S' initially opened as shown in the figure. A positive point charge 'Q' is fixed at a distance 2R from the centre of the shells. At t=0, the switch ' S ' is closed till the steady state is reached. Then choose the correct options(s)

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MEDIUM
IMPORTANT

A fuse made of lead wire has an area of cross-section 0.3 mm2 on short circuiting the current in the fuse wire reaches 30 A. How long (in milli second) after the short circuiting, Will the fuse begin to melt ?
For lead, specific heat =0.022calg-1C0-1, melting point =3270C, density =2 g cm-3 and the resistivity =22×10-6Ωcm. The initial temperature of the wire is 270C (neglect heat losses)

MEDIUM
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Two bulbs 25 W-220 V and 100 W-220 V are given. Which has higher resistance?

EASY
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An electric iron of 750 W Power is connected to a 220 V Mains. The current drawn by the iron is nearly.

MEDIUM
IMPORTANT

In Joules's heating law, when R, and t, are constant. If H, is taken along the y, axis and I2,along x,axis. The graph is

EASY
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Two heating wires of equal length are first connected in series and then in parallel. If the combinations are separately connected across the same time. The ratio of heat produced in the first case to that on the second is. 

EASY
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Three equal resistors connected in series with a source of emf together dissipate 10 W of power. The power dissipated by these resistors connected in parallel will be

EASY
IMPORTANT

Of the two bulbs used in a house one glows more brightly than the other. Then which of the following statements is true ?

EASY
IMPORTANT

An electric iron of 750 W Power is connected to a 220 V Mains. The current drawn by the iron is nearly.

EASY
IMPORTANT

Three equal resistors connected in series with a source of emf to-gather dissipate 10 W of power. The power dissipated by these resistors connected in parallel will be