Heating Effects of Electric Current

Q. In an electrical circuit two resistors of 2 $\Omega$ and 4 $\Omega$ respectively are connected in series to a 6 V battery. The heat dissipated by the 4 $\Omega$ resistor in 5 s will be:

1. $5\text{J}$
2. $10\text{J}$
3. $20\text{J}$
4. $30\text{J}$

Q.

Which of the following is the best material for an electromagnets core?

1. Air

2. Steel

3. Soft iron

4. Copper-Nickel alloy

Q. The relation between the temperature ($\text{T}$) of a fuse wire and the current ($\text{I}$) passing through it, is given by $\Delta \text{T}\propto {\text{I}}^2$, at constant resistance.

Which of the following plots correctly represents the relation?

1. 
2. 
3. 
4. 

Q.

Name four electrical devices which makes use of heating effect of current.

Q.

What is a fuse? Why is it called a safety device?

Q.

What happens to the heat produced in a conductor when current is doubled?

1. Is doubled

2. Becomes 3 times

3. Becomes 4 times

4. Is unaffected

Q. The shape of magnetic field lines around a straight current carrying wire is ___.

1. concentric circles
2. elliptical curves
3. parallel lines
4. a grid of parallel and perpendicular lines

Q.

A coil having 12 turns is connected to a battery as shown. The magnetic field at the axis of the helix will be ___ the magnetic field at the center of a similar circular loop but with a single turn.

1. greater than
2. lesser than
3. equal to
4. opposite in direction to

Q. A heater joined in parallel with a 60 watt bulb is connected to the mains. If the 60 watt bulb is replaced by a 100 watt bulb, will the rate of heat produced by the heater remain the same in comparison to the first case? Do not reject it

Q.

What happens when the current is switched ‘on’ in a room heater?

Q.

Magnetic poles always occur in pairs.

1. True
2. False

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

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

Q. Fuse should be connected to ______ wire of the circuit.

1. ground
2. neutral
3. neutral and live both
4. live

Q.

What is converted into heat when current is set up through a conductor?

1. Electric current

2. Electric potential

3. Electric energy

4. Electric resistance

Q. Filament of a bulb is made up of tungsten.

1. False
2. True

Q. For a fuse rated at 10 A, the fuse melts if the current in the circuit exceeds A.

1. 5
2. 10
3. 1
4. 100

Q. A shorter wire has a higher resistance than a longer wire of the same thickness and same material.

1. True
2. False

Q. What does a 5 A rating on a fuse mean?

1. Fuse melts down if the current is less than 5 A.
2. Fuse melts if the current is more than 5 A.
3. Fuse allows a current only equal to 5 A through it.
4. Fuse produces energy if current is less than 5 A.

Q. When a bulb glows it emits both heat and light.

1. False
2. True

Q. Heating in current carrying conductor is a product of and time.

1. current
2. resistance
3. power

Q. In a bulb, electrical energy is converted into .

1. potential energy
2. kinetic energy
3. light energy

Q. A longer wire has a higher resistance than a shorter wire of the same thickness and same material.

1. True
2. False

Q. Fill in the blanks:
The safety device based on heating effect of electric current is called ..........

Q.

When the current in a conductor is doubled keeping other parameters constant, the heating effect of the current will become:

1. is doubled

2. becomes 3 times

3. becomes 4 times

4. is unaffected

Q. Telephone is example of

1. circuit switching
2. message switching
3. All of the above
4. packet switching

Q. What does a 5 A rating on a fuse mean?

1. Melts if electric current, I > 5 A
2. Burns down if electric current, I < 5 A
3. Can function only if electric current, I = 5 A
4. Does not indicate anything

Q. Explain :
Why is the tungsten used almost exclusively for filament of electric lamps?

Q. Which of the following devices work on the heating effect of electric current?

1. Fan
2. Radio
3. Geyser
4. Phone
5. Bulb
6. Oven
7. Switch
8. Electric iron
9. Cell
10. Toaster

Q.

Which effect is utilized by an electric bulb?

1. Chemical effect

2. Heating effect

3. Power effect

4. Magnetic effect

Q.

What happens to the heat produced in a conductor when current is doubled?

1. Is doubled

2. Becomes 4 times

3. Becomes 3 times

4. Is unaffected