Electrical Resistivity and Electrical Conductivity

Q.

Unit of electric power may also be expressed as

1. Volt ampere

2. Kilowatt hour

3. Watt second

4. Joule second

Q.

What determines the rate at which energy is delivered by a current?

Q.

An Electric Bulb Of Resistance $200\Omega$ Draws A Current Of $1$ Ampere. Calculate The Power Of The Bulb The Potential Difference At Its Ends And The Energy In Kwh Consumed Burning It For $5\mathrm{H}$.

Q. How much energy is transferred when $10A$ current flows through a resistor of resistance $5\Omega$ for time of $30minutes$?

1. 0.25 kWh

2. 3.2 kWh

3. 0.025 kWh

4. 1.2 kWh

Q. When length of a wire and area of cross-section both are doubled, then its resistance will ______.

1. reduce to half
2. increase twice
3. remain same
4. increase four times

Q.

Question 12
If the current I through a resistor is increased by $100\%$ (assume that temperature remains unchanged), the increase in power dissipated will be

(a) $100\%$
(b) $200\%$
(c) $300\%$
(d) $400\%$

Q.

What is electric power?

Q. Question 12
If the current I through a resistor is increased by $100\%$ (assume that temperature remains unchanged), the increase in power dissipated will be

(a) $100\%$
(b) $200\%$
(c) $300\%$
(d) $400\%$

Q.

A wire of resistance $2\Omega$ is stretched to double its length such that its volume remains constant. What is the resistance of the stretched wire?

1. $2\Omega$

2. $8\Omega$

3. $6\Omega$

4. $10\Omega$

Q. Masses of three wires of copper are in the ratio 1 : 3 : 5 and their lengths are in the ratio of 5 : 3 : 1. The ratio of their electrical resistances are

1. $1:3:5$
2. $5:3:1$
3. $1:15:125$
4. $125:15:1$

Q.

What is the resistance of a circuit with voltage 40 V and current 8 A?

1. 5 ohm

2. 32 ohm

3. 10 ohm

4. 32 ohm

Q.

If a metallic wire of resistance R is melted and recast to half of its length, the new resistance of the wire will be?

1. $\frac{R}{4}$

2. $\frac{R}{2}$

3. 2R

4. R

Q. Match the resistances that an ideal conductor offers at different temperatures.

1. Zero resistance
2. Low resistance
3. High resistance

Q. Find the resistance of a hollow cylindrical pipe of length 1 m whose inner and outer radii are 10 cm and 20 cm respectively. Assume that the cylindrical pipe is made of a material of resistivity $2\times {10}^{-8}\Omega m$.

1. $0.21m\Omega$

2. $0.21\Omega$

3. $0.21\mu \Omega$

4. $21\Omega$

Q. Circuit 1 and circuit 2 consists of resistor $R_1$ and $R_2$ respectively. These resistors have same resistivity and thickness. Length of $R_1$ > length of $R_2$. If same voltage is applied across the circuits, which circuit has more current?

1. Circuit 1
2. Equal currents
3. Insufficient information
4. Circuit 2

Q. Find the ratio of the maximum to the minimum resistance for a combination of 'n' equal resistors.

1. $n^2$
2. $\frac{1}{n}$
3. n
4. $\frac{1}{n^2}$

Q. If $150{\text{J s}}^{-1}$ is required for an appliance to run, what is the power consumed by it, if it is operated at $240\text{V}$?

1. $24\text{W}$
2. $150\text{W}$
3. $15\text{W}$
4. $360\text{W}$

Q.

A bulb is joined to a battery of emf 4 V and internal resistance of 2.5 Ω.A steady current of 0.5 A flows through circuit. calculate-

(a) Total energy provided by battery in 10 minutes

Q. The factor(s) affecting the resistance of a conductor is/are:

1. Length of the conductor
2. Area of cross-section of the conductor
3. Material of the conductor
4. Color of the conductor