Voltage Basics
What is the unit of voltage?
Volt (V)
Which quantity describes the energy supplied by a battery?
e.m.f.
What is the symbol used to represent electrical potential difference in a circuit?
V
Write the equation for e.m.f.
E = W/Q
Where is the voltmeter connected to measure the p.d. across a component?
In Parallel
What does voltage tell us about energy and charge?
It tells us how much energy is transferred per unit charge.
What does a voltmeter measure?
Potential difference/voltage.
How is a voltmeter connected?
In Parallel
Write the equation for p.d.
V = W/Q
What happens if the voltmeter is connected in series?
It is connected incorrectly and will not give the intended measurement.
What is another name commonly used for voltage?
Potential difference (p.d.)
Is e.m.f. measured in volts?
Yes
The expected voltage is 8 V. Available ranges are 2 V, 20 V and 200 V. Which should you choose?
20 V.
A source transfers 100 J to 20 C. Calculate the e.m.f.
5V
Which component in this circuit should the voltmeter be connected across to measure the voltage of the lamp?
The lamp
What does 5 V mean?
5 joules of energy are transferred per coulomb of charge.
Explain one difference between e.m.f. and p.d.
e.m.f. is the energy supplied by a source per unit charge, while p.d. is the energy transferred per unit charge through a component.
What is the difference between a voltmeter and an ammeter?
A voltmeter measures p.d.; an ammeter measures current
A resistor transfers 90 J when 15 C passes through it. Calculate the p.d.
6V
A circuit contains a battery and a resistor. What instrument should be used to measure the p.d. across the resistor?
A Voltmeter
A component has a voltage of 12 V. How much energy is transferred when 3 C of charge passes through it?
36 J
A battery has an e.m.f. of 9 V and a lamp has a p.d. of 9 V. Explain what each value means.
The battery supplies 9 J per coulomb, while the lamp transfers 9 J per coulomb.
Explain why a voltmeter is connected in parallel rather than in series.
A voltmeter measures the potential difference between two points, so it must be connected across the component.
A lamp has a p.d. of 12 V. If 4 C of charge passes through it, calculate the energy transferred.
A 9 V battery is connected to two resistors in series.
The p.d. across Resistor A is 3 V.
Calculate the p.d. across Resistor B.
6V