Electricity_Magnetism__test_2006

2. Complete the following poem:

All Physics students should learn well This scientific fact:

Like magnetic poles repel

And unlike poles _______________

3. Multiple choice questions –

Charged matter has (a) No electricity (b) Moving electricity (c) Static electricity

(d) Unbalanced numbers of electrons and protons

Which of the following would destroy magnetism of a bar magnet? (a) Dropping it or hammering it

(b) Passing an alternating electric current through it (c) Sawing it into several pieces (d) Heating it with a Bunsen burner

A positively charged object has (a) Positive (plus) charges only (b) More plus than minus charges (c) More minus than plus charges

(d) An equal number of positive and negative charges.

If you magnetise a steel bar by stroking it with the North end of a magnet, the place marked (see below) becomes

(a) The North Pole (b) The South Pole (c) The Neutral Point (d) It cannot be determined

A direct current of 6 amps is passed through two long, thin, parallel wires that are separated by a distance of 3 mm. the current is flowing in the same direction in both wires. The wires are observed to move slightly towards each other indicating a force of attraction.

What is this force of attraction due to? a) A magnetic field created around each wire by direct current b) The electric field created around each wire by direct current c) The force of gravitational attraction between the 2 wires d) The forces of attraction between atoms in each wire e) The forces of attraction between the nuclei of atoms to passing electrons in each wire.

The diagrams show a small Styrofoam ball P ball hanging by a silk thread. A plastic strip S

is held close to the ball.

(a)

(b)

(c)

(d) (e)

In which diagram/s could S and P both carry a positive charge? ______________ In which diagram/s could S and P both carry a negative charge? ______________ In which diagram/s could S carry NO charge and P carry a positive charge? ___________ In which diagram/s could S and P both carry NO charge? ___________

In which diagram/s could S carry a negative and P carry NO charge? ___________

Name the device the girl is touching and explain why her hair is on end

How does the dome build up charge?

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When we rub two different materials together, which becomes positively charged and which becomes

negative? Scientists have ranked materials in order of their ability to hold or give up electrons. This ranking If paper becomes positively charged when rubbed with silk,

what charge will the silk get? _________________ Which two materials will provide the greatest charge, when rubbed together, and what charges will they have? Use the Triboelectric series shown to explain your answer. __________________________________________________ __________________________________________________ __________________________________________________

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Current can only flow in an electrical circuit when there is an unbroken path from the positive side of the power supply to the negative side.

A switch can break the path along which a current can flow in an electrical circuit .

The circuit represents the wiring in a house. Globes P, Q and R are in different rooms, A switch or switches need to be installed so that only globe R will go out when the switch is off.

On the diagram show which locations a switch/switches be placed, using the correct symbol.

An electric current flowing through a circuit behaves similarly to water flowing through a network of pipes.

For example

in a circuit allows electric current to move through wires. The battery is similar to a pump that

moves water (electrical current) through pipes (wires)

flow through pipes.

quantity of water passing through it per second.

Given this similarity, list the ammeters in the diagram in order from maximum to minimum electric current. Assume each resister is of the same value. If you feel the readings on any ammeter are identical, place brackets around the ammeters; eg (A1, A 4) would indicate that you think the readings of ammeter 1 and 4

Multiple choice questions –

Which of the following would give the strongest electromagnet?

(a) 10 coils of wire wound in the same direction

(b) 10 coils of wire wound in the same direction with

an iron core

(c) 5 coils wound one way, 5 coils wound in the

opposite way

(d) 5 coils wound one way, 5 coils wound in the

opposite way with an iron core

Short answer questions:

Look carefully at the 4 coils below, all of which have the same current passing through them. Which one

(a) gives the weakest electric field? _____________ (b) has a north pole at the left side of this paper?

___________________

(c) Will still give a magnetic field when the current is

switched off? _______________

To make 100 minus charges neutral, you would need

(a) 50 minus and 50 plus charges (b) 100 minus charges (c) 100 plus charges (d) 100 neurons

Use the relationship: V = IR to calculate the unknowns:

(a) A current of 3 amps flows through a 6 Ω resister. What is the voltage across the resistor?

(b) An iron is plugged into our 240 V mains, and a current of 10 amps flows through the element.

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