Heating Effect of Current

Q.

When the current in a conductor is doubled, keeping its resistance constant, the heat generated in the conductor will be:

1. is doubled

2. is unaffected

3. becomes 4 times

4. becomes 3 times

Q. For a constant resistance, the correct relation between heat produced ($\text{H}$) and electric current ($\text{I}$) flowing is:

(a) $\text{H}\propto \text{I}$
(b) $\text{H}\propto {\text{I}}^{-1}$
(c) $\text{H}\propto {\text{I}}^2$
(d) $\text{H}\propto {\text{I}}^{-0.5}$

[1 mark]

Q.

Tungsten is used almost exclusively for filament of incandescent lamps because tungsten has a high melting point (${3380}^{\circ }$C) and becomes incandescent (i.e., emits light at a high temperature) at 2400 K.

1. False
2. True

Q.

We have an electric kettle rated at (60v, 5A). We have a mass of 10 kg that is placed such that the steam in the kettle is used to drive the mass in the horizontal direction.If the kettle runs for 5 minutes.What is the velocity of mass attained?

1. 30√20 m/s

2. 60√20 m/s

3. 100 m/s

4. 50 m/s

Q.

For a constant resistance, the correct relation between heat produced (H) and electric current (I) flowing is:

1. $\text{H}\propto \text{I}$
2. $\text{H}\propto {\text{I}}^{-1}$
3. $\text{H}\propto {\text{I}}^2$
4. $\text{H}\propto {\text{I}}^{-0.5}$

Q. Heat energy dissipated across a conductor carrying current I, having resistance R for a time t, is given by:

1. $IR$
2. $I^{2}R$
3. $I^2{R}^{2}t$
4. $I^{2}Rt$

Q.

When electric current flows through a conductor, the conductor gets

1. hot

2. cold

3. breaks into pieces

4. None of these

Q.

In electric heating appliances the material of the heating element is

__

Q.

Find the resistance of an electric motor which when connected across a battery of 6 volts for 1 min runs with 216 Joules of energy

1. 5Ω

2. 6Ω

3. 36Ω

4. 10Ω

Q. If a heater of resistance $100\Omega$ draws a current of $5A$ for $1hour$, then the energy consumed by the heater is:

1. $3600kJ$
2. $9000kJ$
3. $2500kJ$
4. $1800kJ$