Electricity and Circuits Test

Result

Electricity and Circuits Test - 10

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Weekly Quiz Competition

Question 1
1 / -0

What happens to a circuit when the switch is off?

A
The circuit is complete

B
There is a gap in the circuit

C
Electricity flows continuously

D
Electricity flows discontinuously

Solution

The switch acts as a connecting part of a circuit. When the switch is off, the circuit is incomplete as the connection is broken in the place of the switch. So, no current can pass through this broken circuit.
Question 2
1 / -0

The metal disc provided at; one end of the common cell is the:

A
switch

B
positive terminal

C
negative terminal

D
spring

Solution

The metallic disc at lower end of common cell is at lower potential than the upper cap of cell and is termed as negative terminal .

Answer-(C)
Question 3
1 / -0

Substances that do not allow free flow of charge through them are called __________.

A
Insulators

B
Conductors

C
Both A and B

D
None of these

Solution

Substances that do not allow free flow of charge (i.e. electron) through them are called insulator.
For example:- Plastic, wood
Question 4
1 / -0

A bulb rated 240 V, 100 W is connected to a 120V supply. What can be inferred?

A
The bulb fuses

B
The bulb lights up but it is dim

C
The bulb lights up to normal brightness

D
The bulb lights up initially and then it fuses

Solution

Rating of bulb
$$P=100W$$
$$V=240V$$
$$P=\dfrac{V^2}{R}$$
$$R=\dfrac{V^2}{P}$$
$$R=\dfrac{240^2}{100}$$=$$576\Omega$$
Also
$$P=VI$$
$$100=240\times I$$
$$I$$=$$0.416A$$
So the bulb has a resistance of $$576\Omega$$ and can tolerate a current of $$0.416A$$
Now supply=$$120V$$

$$V=IR$$
$$120=I\times 576$$
$$I=0.208A$$.....which is less than rated current $$0.416A$$ hence the bulb will not fuse.
It will light up but dim because $$120V$$is supplied instead of rated $$240V$$
Question 5
1 / -0

The given figure is a 'material tester'.
Which of the following objects will make the bulb glow when put on the gap shown?

A

B

C

D

Solution

The nail will make the bulb glow.
Because it is made up of metal, and we know that metals are good conductors of electricity. Other options are not good conductors of electricity.
So, only the nail will allow electricity to pass through it.
Question 6
1 / -0

What type of energy transformation occurs in a dry cell ?

A
electrical to thermal energy

B
chemical to electrical energy

C
electrical to light energy

D
potential to electrical energy.

Solution

In a zinc-carbon dry cell there is a electro-chemical reaction between zinc and manganese dioxide. A carbon rod collects the current from the manganese dioxide electrode. Thus chemical energy is converted into electrical energy. Option B is correct.
Question 7
1 / -0

Nidhi has two bulbs connected across two cells in a simple circuit. How can she make the bulbs glow dim?

A
Replace one cell with a piece of chalk

B
Replace one cell wtih a piece of wire

C
Replace one bulb with a piece of wire

D
Replace one bulb with another cell
Question 8
1 / -0

Substances which allow electricity to pass through them are known as

A
Electrical conductors

B
Electrical insulators

C
Both conductors & insulators

D
None of these

Solution

Substances which allow electricity to pass through them easily are called conductors of electricity or electrical conductors.For example:Silver,Copper,Aluminium,etc.
Question 9
1 / -0

If we touch a naked current carrying wire, we get a shock. This is because our body is a :

A
conductor of electricity

B
insulator of electricity

C
source of electricity

D
both B&C

Solution

We get a shock because electric current passes through our body because our body is a conductor of electricity.

Answer-(A)
Question 10
1 / -0

Pooja connects a second cell in a simple circuit, how will this effect the brightness of the bulb?

A
It will stop glowing

B
It will cause the bulb to fus

C
It will become dimmer.

D
It will become brighter

Solution

When Pooja connects the second cell in a simple circuit, then the second cell provides additional energy to the circuit, and the bulb gets more power to glow. Subsequently the brightness of the bulb increases.
For example, a torch with a single-cell provides less light compared to a torch with double cells.