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Form 2 Physics Magnetic Effect of Electric Current Questions and Answers
Show the direction of the magnetic field in the conductor carrying current shown below.
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1.
a) The figure below shows a motor connected to a magnetic switch called a relay operated by an ordinary S switch S1. Use the information in the figure to answer questions that follow. i).Explain how the relay switches on the motor when S1 is closed. ii) State with a reason the effect on the motor if the iron core is replaced with a steel core and switch S1 is put on and then off.
2.
The diagrams below show a soft iron plate in a solenoid and a permanent magnet suspended by a spring. State with reason the behavior of the magnet when the switch S is closed.
3.
The figure below shows an electromagnetic relay being used to switch an electric motor on and off. The electromagnet consists of a coil of wire wrapped around a core. The motor in figure is switched off.
4.
Show the direction of the magnetic field in the conductor carrying current shown below.
5.
The diagram below shows a conductor in a magnetic field. Indicate on the diagram the direction of motion.
6.
The coil of an electric motor is usually wound on a soft iron armature. State the reason for use of soft iron.
7.
A metre rule is suspended by a thread such that it in equilibrium balanced by a permanent magnet attached to the metre rule and some weight as shown in the figure below. If the soft iron is fixed to the bench, state and explain the effect on the metre rule when the switch is close.
8.
The figure below shows a current carrying vertically right wire at right angle to a cardboard. Iron fillings are sprinkled on the card and card slightly tapped. Draw and indicate the direction of the magnetic field pattern displayed on the card.
9.
The figure below shows the circuit of a simple telephone receiver. Explain how the telephone receiver works
10.
The figure below shows an electromagnetic relay. Explain what happens when the switch is closed.
11.
The force on a conductor carrying current in a magnetic field can be varied by changing among others, the magnitude of the current and the magnetic field strength. Name other factors that can be changed to vary the force.
12.
The figure below two parallel current conductors A and B placed close to each other. The direction of the current is into the plane of the paper. On the same figure; i).Sketch the magnetic field ii).Indicate the force F due to the current on each conductor.
13.
In an experiment to determine the strength of electromagnet, the weight of pins that can can be supported by the electromagnet, was recorded against the number of turns. The current was kept constant throughout the experiment. The table below shows the data obtained. i).Plot a graph of weight W against the number of turns, ii).Use the domain theory to explain the nature of the curve. iii).Sketch
14.
The figure below shows XY at right angles to a magnetic field. XY is part of circuit containing a galvanometer. When XY is moved the current flows in the direction shown. State the direction in which XY is moved.
15.
The figure below shows a soft-iron ring placed between the poles of a magnet. On the same diagram, sketch the magnetic field pattern.
16.
The figure bellow shows two parallel thick copper conductors connected to a d.c power supply. State and explain what is observed on the rider when the switch is closed.
17.
The figure below shows a solenoid carrying an electric current. Sketch the magnetic field pattern inside and at the ends of the solenoid.
18.
The figure below shows two similar coils P and Q around the end L and M of a piece of soft iron. A steady current passes through the coils. State the polarity of the resulting magnet at point L.
19.
The figure below shows a diagram of a current-carrying wire wound on a U-shaped soft iron. Draw the magnetic field pattern around P and Q.
20.
The figure below shows an incomplete circuit of an electromagnet. Complete the circuit between X and Y by drawing the windings on the two arms of the core such that A and B are both North poles when the switch S is closed. Indicate the direction of the current on the windings drawn.
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