Current Electricity

We know the relation between current (I), charge (Q), and time (t): Given: Q = 6 C, t = 2 minutes = 120 seconds Substitute into the formula:

The correct option is (C):

The relationship between potential difference (V) and current (I) is given by Ohm's Law. Ohm's Law states that: where:
V = Potential Difference (Volts)
I = Current (Amperes)
R = Resistance (Ohms)

This law was formulated by the German physicist Georg Simon Ohm.

The correct option is (D): Ohm

Correct answer: 30 V

Explanation:
Using Ohm’s Law:
where:
(current)
(resistance)

Substituting the values:

Hence, the potential difference across the conductor is: 30 V.

Correct answer: Units of both resistivity and resistance are the same.

Explanation:
Let’s examine each statement:

1. Resistivity is also called specific resistance – True
Resistivity is indeed another name for specific resistance. It is a material property.

2. Reciprocal of resistivity is called conductivity – True


3. Units of both resistivity and resistance are the same – False
- Resistance unit: (ohm)
- Resistivity unit: (ohm-meter)
So, the units are not the same.

4. Low resistivity metals are good conductors – True
Good conductors like copper and silver have very low resistivity.

Hence, the false statement is: Units of both resistivity and resistance are the same.

Correct answer: 1 volt

Explanation:
By definition, electric potential (voltage) is the work done per unit charge to move a charge between two points. Mathematically, So,
Hence, the correct answer is: 1 volt.

The unit of measure for electrical resistance is the "ohm." It is defined as the resistance between two points of a conductor when a constant potential difference of 1 volt, applied to these points, produces a current of 1 ampere through the conductor. Therefore, volt per ampere is called ohm.
This relationship can be represented by Ohm's Law, which is expressed as:

R =

where is the resistance in ohms, is the voltage in volts, and is the current in amperes.
Hence, among the given options watt, ohm, coulomb, and joule, the correct answer is ohm.

• Battery: A battery is designed to maintain a constant potential difference across its terminals by converting chemical energy into electrical energy. Thus, it consistently provides voltage.
• Multimeter: This device measures electrical properties like voltage, current, and resistance. It does not maintain a potential difference.
• Ammeter: An ammeter measures current in a circuit; it doesn't maintain a potential difference.
• Electric Bulb: This device converts electrical energy into light and does not maintain a potential difference.

Therefore, the correct choice is a Battery because it consistently maintains a potential difference across its terminals.

A fuse in an electrical circuit is a safety device designed to protect the circuit from excessive current. When the current exceeds a certain level, the fuse 'blows' or melts, breaking the circuit and stopping the flow of electricity. This action prevents damage to the electrical components or even fires.

The construction of a fuse involves using a thin wire of low melting point. The reasoning behind this is tied to the operational principle of the fuse:

• When an excessive current flows through the circuit, the electrical energy generates heat according to the formula Q = I²Rt, where Q is the heat energy, I is the current, R is the resistance, and t is the time.
• The wire in the fuse is intentionally thin, making its resistance higher, and thus, it heats up more quickly when the current increases.
• The wire is made from a material with a low melting point. This ensures that the fuse wire melts when the temperature exceeds the safe limit due to excessive current, ensuring rapid disconnection of the circuit.

This design facilitates efficient protection of the electrical setup by promptly interrupting overcurrent conditions before they can cause harm.

A multimeter is used to measure several electrical properties, including: - Voltage, - Current, and - Resistance. However, a multimeter does not measure electric charge. Electric charge is typically measured using a different instrument called a coulomb meter.

Thus, the correct answer is Charge.