1. Ohm's law relates:
Answer:
Explanation:
Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points.
2. The resistance of a wire is R. If its length is doubled without changing the volume, the new resistance will be:
Answer:
Explanation:
Resistance is directly proportional to length and inversely proportional to the area of cross-section. Doubling the length will double the resistance, but halving the area will quadruple the resistance.
3. The unit of electric current is:
Answer:
Explanation:
The SI unit of electric current is Ampere.
4. The resistivity of a material:
Answer:
Explanation:
For metals, resistivity generally increases with temperature, but for semiconductors, it decreases.
5. Kirchhoff's first law is based on the conservation of:
Answer:
Explanation:
Kirchhoff's first law, also known as the junction rule, states that the sum of currents entering a junction is equal to the sum of currents leaving the junction, which is based on the conservation of electric charge.
6. The reciprocal of resistance is:
Answer:
Explanation:
Conductance is the inverse of resistance and represents a material's ability to conduct electric current.
7. In a series circuit with resistors of unequal values:
Answer:
Explanation:
In a series circuit, the current remains constant across all components.
8. A device that converts electrical energy into mechanical energy is:
Answer:
Explanation:
A motor is a device that converts electrical energy into mechanical energy.
9. The power in an electrical circuit is given by:
Answer:
Explanation:
The power in an electrical circuit can be expressed as P = V^2/R or P = I^2R, depending on the known variables.
10. The drift velocity of electrons in a conductor is directly proportional to:
Answer:
Explanation:
Drift velocity is directly proportional to the electric field in the conductor, which is, in turn, proportional to the current.
11. Superconductors are materials:
Answer:
Explanation:
Superconductors are materials that exhibit zero resistance to the flow of electric current below a specific critical temperature.
12. The potential difference across a resistor carrying a current is 12V. If the power dissipated is 36W, what is the value of the current?
Answer:
Explanation:
Using the formula P = V*I, the current I = P/V = 36W/12V = 3A.
13. Which of the following materials has the highest resistivity?
Answer:
Explanation:
Rubber is an insulator and has much higher resistivity than metals like silver, copper, and iron.
14. A cell of emf 'E' and internal resistance 'r' is connected to an external resistance 'R'. The current in the circuit is maximum when:
Answer:
Explanation:
The current will be maximum (I = E/(r+R)) when the external resistance R is zero.
15. In the case of an ideal voltmeter, its resistance is:
Answer:
Explanation:
An ideal voltmeter has infinite resistance so that it does not draw any current from the circuit it's measuring.
16. The effect by which a current in one coil induces a current in a nearby coil is known as:
Answer:
Explanation:
Mutual induction is the phenomenon where a change in current in one coil induces a current in a nearby coil due to their mutual magnetic fields.
17. A wire of resistance 4 ohms is bent to form a circle. The resistance between any two points on the circle, diametrically opposite to each other is:
Answer:
Explanation:
When diametrically opposite points are connected, the current will take two equal paths. The effective resistance becomes half, i.e., 2 ohms.
18. A resistor is connected across a 60V source. If a current of 4A flows through the resistor, its value is:
Answer:
Explanation:
Using Ohm's law, V = IR. Therefore, R = V/I = 60V/4A = 15 ohms.
19. The color bands on a resistor represent:
Answer:
Explanation:
The color bands on a resistor typically indicate its resistance value, tolerance, and sometimes its power rating.
20. In an AC circuit, the current that leads or lags behind the voltage is due to:
Answer:
Explanation:
In an AC circuit, inductance causes the current to lag behind the voltage, while capacitance causes the current to lead the voltage.