Current Potential Difference Resistance

What is the rate of electric charge flow in a circuit called?

• Electric current

• Electric resistance

• Electric voltage

• Electric power

Answer explanation

The rate at which electric charge flows in a circuit is called electric current. It is measured in amperes (A) and is a fundamental concept in understanding how electrical circuits operate.

Which instrument measures current in an electric circuit?

• Voltmeter

• Ammeter

• Thermometer

• Barometer

Answer explanation

An ammeter is specifically designed to measure the current flowing through an electric circuit. In contrast, a voltmeter measures voltage, while a thermometer and barometer measure temperature and atmospheric pressure, respectively.

What is the SI unit of electric current?

• Volt

• Ohm

• Ampere

• Watt

Answer explanation

The SI unit of electric current is the Ampere, often abbreviated as 'A'. It measures the flow of electric charge. Volt measures electric potential, Ohm measures resistance, and Watt measures power.

How is an ammeter connected in a circuit to measure current?

• In parallel

• In series

• Across the battery only

• Across the bulb only

Answer explanation

An ammeter must be connected in series with the circuit to measure the current flowing through it. This allows the ammeter to measure the total current without altering the circuit's operation.

What causes the flow of electric charge in a circuit?

• Movement of protons

• Movement of electrons

• Movement of neutrons

• Movement of atoms

Answer explanation

The flow of electric charge in a circuit is caused by the movement of electrons in the wires. Electrons are negatively charged particles that move through conductive materials, creating an electric current.

Why do electrons move in one direction when a battery is connected in a circuit?

• Because the battery heats the wires

• Because the battery creates a magnetic field

• Because the battery provides a potential difference

• Because the battery increases resistance

Answer explanation

Electrons move in one direction when a battery is connected because the battery provides a potential difference, creating an electric field that drives the flow of electrons through the circuit.

How should an ammeter be connected in a circuit?

• Negative terminal to the positive side of the cell and positive terminal to the negative side

• Both terminals to the same side of the cell

• Negative terminal to the negative side of the cell and positive terminal to the positive side

• The ammeter is not connected to the cell

Answer explanation

The correct way to connect an ammeter is in series with the circuit, ensuring the negative terminal connects to the negative side of the cell and the positive terminal to the positive side. This allows accurate current measurement.

What is the energy needed to move a unit charge in a circuit?

• Current

• Resistance

• Power

• Potential difference (Voltage)

Answer explanation

The term for the amount of energy needed to move a unit charge in a circuit is called potential difference, or voltage. It quantifies the energy per charge, distinguishing it from current, resistance, and power.

How is the flow of water in a tank similar to the flow of electric charge in a circuit?

• Both require a filter.

• Both involve energy to move something.

• Both are controlled by temperature.

• Both use gravity as the only force.

Answer explanation

The flow of water in a tank system and the flow of electric charge in a circuit both require energy to move substances from one point to another, highlighting their similarity in energy transfer.

What instrument measures the potential difference in an electric circuit?

• Ammeter

• Voltmeter

• Thermometer

• Barometer

Answer explanation

A voltmeter is specifically designed to measure the potential difference (voltage) between two points in an electric circuit, making it the correct choice. An ammeter measures current, while a thermometer and barometer measure temperature and pressure, respectively.