Electric Current

Q.

What do you understand by the term current ? State and define its S.I.unit.

Q.

Calculate the current flowing through a wire of resistance 5 Ω connected to a battery of potential difference 3 volt.

1. $0.2A$

2. $0.4A$

3. $0.6A$

4. $0.8A$

Q. Distinguish between:
Electric current & Potential difference

Q.

Electric current is only due to the flow of electrons.

1. True

2. False

Q.

The physical quantity whose unit is coulomb per second is ___.

1. resistivity

2. resistance

3. potential difference

4. current

Q.

Electric current flows only when a circuit is closed.

1. True
2. False

Q.

Calculate the current flowing through a wire of resistance 7.5 Ω connected to a battery of potential difference 1.5 V.

1. $0.1A$

2. $0.2A$

3. $0.3A$

4. $0.4A$

Q.

A charge of $420C$ flows through a conducting wire in 5 minutes. Find current flowing through the conductor.

1. 1.2 A

2. 1.4 A

3. 1.6 A

4. 1 A

Q.

Free electrons flow in the direction of current.

1. True
2. False

Q.

Fig. 9.26 below shows two conductors A and B. Their charges and potentials are given in the diagram. State the direction of (i) flow of electrons, and (ii) flow of current, when both the conductors are joined by a metal wire.

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. becomes 4 times

3. becomes 3 times

4. is unaffected

Q.

The wire of an electric kettle carries a current of 10 mA. What is the total number of electrons passing through the wire in 10 minutes?

1. 3.75 × 10¹⁹

2. 4.35 × 10¹⁹

3. .15 × 10⁻¹⁹

4. 2.25 × 10¹⁹

Q. A current of $1A$ is drawn by a filament of an electric bulb. What will be the approximate number of electrons passing through a cross section of its filament in 16 seconds?

1. ${10}^{20}$
2. ${10}^{19}$
3. ${10}^{22}$
4. ${10}^{23}$

Q. Henry Cavendish proposed the amount of electricity as and the intensity of electricity as.

1. current
2. charge
3. voltage
4. mass

Q. Like charges attract while unlike charges repel each other.

1. True
2. False

Q. A conducting wire has electric resistance $‘R^{\prime }$. If the length of this wire and the area of the cross-section are halved, then what will be the new resistance of the wire?

1. $R$
2. $R/2$
3. $2R$
4. $4R$

Q. A simple electric circuit is made by connecting a bulb to a battery using wires. Ammeter and voltmeter are also connected to read the current and the potential difference across the bulb. How should these devices be connected in the circuit?

1. Both ammeter and voltmeter in parallel.
2. Ammeter in series and voltmeter in parallel.
3. Ammeter in parallel and voltmeter in series.
4. Both ammeter and voltmeter in series.

Q.

A conductor $AB$ is joined to a cell with its end $A$ at a low potential and the end $B$ at a high potential. The direction of flow of current in the conductor is from $A$ to $B.$

1. True

2. False

Q. Question 17
When does an electric short circuit occur?

Q. Materials which do not allow charges to flow through them easily are called poor conductors of electricity.

1. False
2. True

Q. A 6V battery is connected to the terminals of a 3 metre long wire of uniform thickness and resistance of 100 ohm. The difference of potential between two points on the wire separated by a distance of 50cm will be

Q.

Which among the following can conduct electricity?

1. Human body
2. A bird
3. Earth
4. None of the above

Q.

what is the direction of current (conventionally and electronically )

Q.

One coulomb charge per second equals to ___ ampere.

1. one

2. Three

3. Four

4. Two

Q.

If a toy fan is connected across a battery for 2 minutes and we know that a charge transfer of 120 C takes place then find out the current in the circuit for that period of time.

1. 240 A

2. 120 A

3. 1 A

4. 60 A

Q. Find the electric current that flows through a conductor if a charge of $0.8C$ flows through it in $4seconds$.

1. $0.5A$
2. $0.2A$
3. $0.25A$
4. $0.01A$

Q. The resistance of the network between the terminals A and B is:

1. $30\Omega$
2. $20\Omega$
3. $60\Omega$
4. $50\Omega$

Q.

Current in circuit flows from:

1. high potential to low potential

2. low potential to high potential

3. positive terminal to negative terminal of cell

4. negative terminal to positive terminal of cell

Q.

The direction of the conventional current is the same as the direction of flow of electrons.

1. True
2. False

Q. Electrons in a circuit always need a closed path to move when a potential difference is applied.

1. True
2. False