4) Electric quantities (p. 12 & 13)

What is voltage?

• The difference in electrical energy between two points
• The number of electrons passing a point
• The amount of heat in a circuit
• The speed of a motor

Answer explanation

Voltage is the energy difference between two points in a circuit.

Which instrument is used to measure voltage?

• Voltmeter
• Ammeter
• Multimeter
• Thermometer

Answer explanation

A voltmeter is used to measure voltage, and it is connected in parallel.

What unit is used to measure voltage?

• Amps
• Volts
• Ohms
• Joules

Answer explanation

Voltage is measured in volts (V).

What unit is used to measure current?

• Amps
• Volts
• Watts
• Ohms

Answer explanation

Current is measured in amperes (A).

What device measures electric current?

• Resistor
• Voltmeter
• Motor
• Ammeter

Answer explanation

An ammeter is used to measure current, and it is connected in series.

What is resistance?

• Opposition to the flow of electric current
• The number of electrons
• The speed of the flow
• None of the above

Answer explanation

Resistance is how much a component blocks the flow of electricity.

How is resistance represented?

• R
• V
• I
• P

Answer explanation

Resistance is represented by the letter R.

What is the symbol for current in formulas?

• I
• R
• V
• P

Answer explanation

The letter I represents electric current.

What is the formula for power?

• P = R × I
• P = V × I
• P = E / t
• P = V / R

Answer explanation

Power is the energy consumed in a unit of time: P = E / t.

Power is measured in...

• Watts
• Amperes
• Joules
• Ohms

Answer explanation

The unit of power is the watt (W).