Question 1
The force on a conductor carrying a current in a magnetic field can be varied by changing, among others, the magnetic field strength and the magnitude of the current. Name two other factors that can cause the force to vary.
Answer
- Length of the coil within the magnetic field
- Precense of a soft iron armature within the coil
- Precense of a soft iron armature within the coil
Question 2
You are provided with a charged electroscope, an insulator and a conductor. Describe how you would use these apparatus to distinguish the insulator from the conductor
Answer
Bring the substances one at a time into contact with the electriscope
Question 3
Figure 1 below shows two mirrors AB and CD placed at an angle of 60o to each other. The ray XY in incident on mirror AB as shown.Figure 1
Sketch on the same diagram the path of the ray after striking mirror AB.
Answer
Question 4
Figure 2 below shows a rigid circuit ABCD suspended by a silk thread from a support. The coil AB is made of copper.Figure 2
The magnet near A is suddenly pulled to the left. State and explain the observation
Answer
The circuit swings to the left induced current creates a south pole at end A of the coil. This is then attracted by the north pole of the magnet
Question 5
The circuit diagram in figure 3below has two switches P and Q. The brightness of the lamp is observed when P only is closed and when P and Q are both closed. Figure 3
Compare the brightness of the lamp in the two cases. State a reason for your answer
Answer
When both P and Q are closed, the bulb is brighter. total resistance decreases thus there is higher potential drop across the lamp and a higher current through the bulb