Electricity - I

What is electricity primarily used for in modern society?

• Illuminating homes.
• Powering automobiles.
• Generating heat for cooking.
• Producing mechanical energy.

In an electric circuit, what happens when the circuit is broken or the switch is turned off?

• The current increases.
• The current becomes erratic.
• The current stops flowing.
• The current reverses its direction.

How is electric current expressed in terms of charge and time?

• I = Q × t
• I = Q / t
• I = Q + t
• I = Q - t

What is the SI unit of electric charge and its equivalent in terms of electrons?

• Coulomb (C); 6 × 10^18 electrons.
• Ampere (A); 1 coulomb of charge.
• Ohm (Ω); 1 joule per coulomb.
• Volt (V); 1 joule per second.

What is the purpose of an ammeter in an electric circuit?

• To regulate the flow of electric current.
• To measure electric potential difference.
• To measure the resistance of a component.
• To measure the electric current.

According to Ohm's law, what is the relationship between potential difference (V), current (I), and resistance (R)?

• V = I × R
• I = V + R
• R = V / I
• V = R - I

What property of a conductor determines its ability to resist the flow of electric charges?

• Temperature.
• Density.
• Length.
• Resistance.

How does the resistance of a uniform metallic conductor depend on its length and area of cross-section?

• It is inversely proportional to length and directly proportional to area of cross-section.
• It is directly proportional to length and inversely proportional to area of cross-section.
• It remains constant regardless of length and cross-section.
• It decreases with length and increases with cross-section.

What does the electrical resistivity (ρ) of a material represent?

• Its ability to conduct electricity.
• Its potential difference with other materials.
• Its ability to resist the flow of electric charges.
• Its ability to generate electric potential difference.

Why are alloys commonly used in electrical heating devices like toasters?

• They have a low resistivity.
• They can easily burn at high temperatures.
• They can withstand high temperatures without oxidizing.
• They are good conductors of electricity.