Motor Effect Past Paper PDF

Motor effect. 1\. The photograph shows a small electric motor. \(a) Explain why the coil starts to spin when the switch is closed. (4) \(b) (i) Suggest how to make the coil spin in the opposite direction. (1) \(ii) Suggest how to make the coil spin more slowly. (1) 2\. (a) State what is meant b...

Motor effect. 1\. The photograph shows a small electric motor. \(a) Explain why the coil starts to spin when the switch is closed. (4) \(b) (i) Suggest how to make the coil spin in the opposite direction. (1) \(ii) Suggest how to make the coil spin more slowly. (1) 2\. (a) State what is meant by the term magnetic field line. (1) \(b) The diagram shows a cross-section through a wire placed between two magnetic poles. The wire carries electric current into the page at X. The shape of the magnetic field is shown. \(i) Add arrows to any two lines to show the direction of the magnetic field. (1) \(ii) Draw an arrow on the diagram to show the direction of the force on the wire. Label this arrow F. (2) \(c) Describe the magnetic field in the region inside the dotted square. (2) 3\. Some students are investigating a simple electric motor. \(a) When the switch is closed the coil spins on the axle. State why. (2) \(b) State two changes that would make the motor spin faster. (2) \(c) The students change their circuit, replacing the cell and switch with a lamp. When they spin the coil by hand, the lamp lights. Explain why the lamp lights. (2) 4\. (a) (i) A magnetic field pattern consists of a number of magnetic field lines. What is shown by the direction of the arrow on a magnetic field line? (1) \(ii) The diagram shows part of the magnetic field pattern for a flat circular coil carrying a current. One of the field lines has its arrow drawn on it. Add an arrow to any other line in the pattern. (1) \(b) The left-hand rule can be used to determine the direction of the force acting on a current-carrying conductor in a magnetic field. \(i) Add the following labels to the diagram below to show what the thumb and the fingers represent: \(ii) State one application of the effect indicated by the left-hand rule. (1) \(c) The diagram below shows a wire carrying a current in the magnetic field between the poles of two bar magnets. \(i) Add an arrow to the diagram to show the direction of the force acting on the wire. (1) \(ii) State two ways in which this force could be increased. (2) 5\. The diagram shows part of a simple electric motor. The motor is connected to a d.c. power supply. \(a) A student predicts that, when the motor is switched on, the coil will turn in a clockwise direction. \(i) Name the rule which the student could use to make this prediction. (1) \(ii) Explain how the rule shows that the coil will turn in a clockwise direction. You may add to the diagram or draw another diagram to help you explain. (2) \(iii) Suggest one change which would make the coil turn faster. (1) \(iv) Suggest one change which would make the coil turn in the opposite direction. (1) \(b) The diagram shows an electric motor lifting a load. Use information from the diagram to answer the following questions. \(i) Calculate the useful work done in lifting the load 0.80 m, and include the unit. (3) \(ii) How much useful energy was transferred to lift the load? (1) \(iii) The total energy transferred by the electric motor was 6.0 J. Suggest two reasons for the difference between this value and your answer to (ii). (2) 6\. (a) An electric current produces a magnetic field. Draw a line from each box to its correct magnetic field pattern. (3) \(b) A charged particle travels towards and enters a magnetic field. \(i) Describe the magnetic force acting on the charged particle when it is moving in the magnetic field. (1) \(ii) Explain your answer. (1) 7\. The diagram shows the inside of a loudspeaker. It contains a cone attached to a coil of insulated wire. The coil is in the gap between the cylindrical poles of a permanent magnet. When there is a current in the coil, both the coil and the cone are forced to move. \(a) Why is the coil made of insulated wire? (1) \(b) (i) In which direction will the coil move? (1) \(ii) State two changes you could make to increase the force acting on the coil. (2) \(c) When the current in the coil changes direction the cone vibrates. \(i) When the cone vibrates at a frequency of 3.6 kHz, what is the frequency in kHz of the sound which is produced? (1) \(ii) Name the unit represented by the symbol kHz. (1) 8\. A wire carries a current. The wire is perpendicular to a magnetic field. A force acts on the wire and the wire moves. \(a) This effect is used in a d.c. motor. \(i) What does the abbreviation d.c. stand for? (1) \(ii) Apart from electric motors, name one other device which uses this effect. (1) \(b) Professor J A Fleming invented a rule to describe the directions involved in this effect. It is known as Fleming's left-hand rule. Complete the sentences. The first finger points in the direction of the \...\...\...\...\...\..... which is from \...\...\...\...\...\...\...\..... to \...\...\...\.... The second finger points in the direction of the \...\...\...\...\.... which is from \...\...\...\...\...\...\..... to \...\...\...\...\...\...... The thumb points in the direction of the \...\...\...\...\...... (5) \(c) State two ways in which the force acting on the wire can be increased. (2) 9\. An electromagnetic force usually acts on a wire which carries a current in a magnetic field. \(a) Name two devices which use this effect. (2) \(b) State two ways in which the force acting on the wire can be increased. (2) \(c) Professor J A Fleming invented a rule to remember the directions involved in this effect. This rule is known as Fleming's left-hand rule. The diagram shows a left hand with two fingers and the thumb extended. Draw a straight line from each of them to the correct box for this rule. (3) \(d) Sometimes a wire carries a current in a magnetic field but no electromagnetic force acts on it. Explain how this can happen. (1) 10\. The diagram shows the magnetic field between magnetic poles X and Y. Use one word in each space to complete the sentences. \(a) The straight, parallel, evenly-spaced lines show that the magnetic field pattern between X and Y is \...\...\...\...\...\...\...\...\...\...\...\...\..... (1) \(b) X is a \...\...\...\...\...\...\.... pole and Y is a \...\...\...\...\...\...\.... pole. (1) \(c) A particle moves through the magnetic field. An electromagnetic force acts on this particle. This shows that the particle must be \...\...\...\...\...\...\...\...\... and that its motion is not \...\...\...\...\...\..... to the magnetic field. (2) 11\. (a) Complete the sentence. A current in a conductor produces a \...\...\...\...\...\...\...\... around the conductor. (1) \(b) The diagram shows a current-carrying wire in a magnetic field. The wire is free to move. A student correctly predicts that when the current is switched on the wire will move out of the page. Name the rule the student used to make her prediction and explain how she used the rule. You may draw a diagram to help to explain your answer. (3) \(c) Give one way to increase the electromagnetic force on a wire in a magnetic field. (1) \(d) A device uses the changing electromagnetic force on a coil of wire in a magnetic field to make a cone vibrate. Name this device. (1) 12.