Electrical Quantities

The unit of electric charge is the coulomb (C). Which combination of other units is equivalent to the coulomb?

The resistance of a wire depends on its length and on its diameter. Which row shows two changes that both increase the resistance of the wire?

A 20″ ” V power supply provides a current of 5.0″ ” A for 1.0 minute. How much energy does the power supply transfer?

A circuit consists of a resistor, a switch and a battery. The switch is closed. Which expression is used to calculate the charge that passes through the resistor?

Four copper wires have different lengths and different cross-sectional areas. Which wire has the smallest resistance?

There is a current of 20″ ” mA in a resistor for a time t. During this time, a charge of 600C passes through the resistor. What is the value of t ?

A power supply causes a current in a circuit. The electromotive force (e.m.f.) of the power supply and the resistance of the circuit are both changed. Which pair of changes must result in a smaller current in the circuit?

What is the unit of charge?

What is the definition of electrical current?

A piece of wire has a resistance of 8.0Ω. The length of the wire is doubled and the diameter of the wire is halved. What is the new resistance of the wire?

How is the resistance R of a wire related to its length l and to its cross-sectional area A? ( ∝ means proportional to)

There is a current of 2.0″ ” A in a resistor. The power produced in the resistor is 8.0″ ” W. What is the potential difference across the resistor?

Four wires are made of the same material. They have different lengths and different cross-sectional areas Which wire has the smallest resistance?

A lamp has a potential difference V across it that causes a current I in it. Which equation gives the power P produced by the lamp?

Three pieces of resistance wire X,Y and Z are made of the same metal. The diagram shows the lengths and the diameters of the wires. What is the order of the wires when they are placed in order of increasing resistance, least resistance first?

The diagram shows a negatively charged oil drop between two metal plates. The plates are connected by an open switch to a power supply. The oil drop is falling at a steady speed. The switch is now closed. What happens to the oil drop?

The diagram shows four wires at the same temperature, made from the same metal. The diagram is drawn to scale. Which wire has the least electrical resistance between its ends?

A negative ion X is close to a positive ion and another negative ion. Electrical forces act on ion X because of the charges in the other two ions. Which diagram shows the directions of the two forces acting on ion X ?

A piece of wire has electrical resistance. The wire is stretched so that it becomes longer and thinner. What, if anything, happens to its resistance?

A torch (flashlight) contains a 3.0″ ” V battery. When the torch is switched on the current in the battery is 0.50″ ” A. How much energy is transferred by the battery in 1.0 minute?

A cell produces a potential difference (p.d.) V across a resistor of resistance R. There is a current I in the resistor. Which expression gives the energy transferred in the resistor in a time t ?

Two identical resistors R_1 and R_2 are connected to a 3.0″ ” V battery as shown. The switch in the circuit is open. The switch is now closed. What happens?

There is a current I in a resistor when there is a potential difference (p.d.) V across it. Which quantity is equal to the product IV ?

There is a potential difference of 4.0″ ” V across a resistor of resistance 2.0Ω. How much charge passes through the resistor in 10″ ” s ?

A lightning strike transfers 20C of charge in 5.0×10^(-4) ” ” s. What is the average current during the lightning strike?

A circuit includes a lamp, a switch and an ammeter. The switch is open. The switch is now closed and the ammeter displays the current reading shown. The switch remains closed for 20 seconds before it is opened again. What is the charge that flows while the switch is closed?

There is a current of 2.0″ ” A in a 4.0Ω resistor for 20″ ” s. What is the charge that flows through the resistor in this time and what is the p.d. across it?

The diagram shows an electric circuit. The battery of electromotive force (e.m.f.) 8.0″ ” V produces a current of 2.0″ ” A in a 4.0Ω resistor. How much power is delivered to the resistor?

There is a current of 0.25″ ” A in a wire. How long does it take for 120C of charge to pass a point in the wire?

A 12″ ” V power supply is connected to a 6.0Ω resistor. This causes a current in the resistor. How much thermal energy is produced in the resistor in 5.0 minutes?

There is a current I in a lamp. The potential difference across the lamp is V and the power produced by the lamp is P. In a second lamp, the current is 2I and the potential difference across it is V/2. What is the power produced by this other lamp?

An electric motor is connected to a 120″ ” V mains supply. The motor transfers 72000″ ” J of energy in 2.0 minutes. What is the current in the motor?

An electric kettle has the following label attached to its base. How is an appropriate fuse for the kettle labelled?