(f) Draw a diagram to show how a galvanometer can be converted into a voltmeter. (g) Give two uses of transistors.
(h) What contribution did George Boole make to modern-day electronics? (i) What is the main energy conversion that takes place in an a.c. generator? (j) Give two advantages of the induction motor over a d.c. motor
‘SECTION B’ FULL QUESTIONS
Q2 A current-carrying conductor experiences a force in a magnetic field. Name the factors that affect the magnitude of the force.
Describe a laboratory experiment to demonstrate the principle that a current-carrying conductor in a magnetic field experiences a force.
The operation of a moving-coil galvanometer is based on this principle. List two other devices based on this principle.
What is the function of a moving-coil galvanometer? Draw a circuit diagram to show how a moving-coil galvanometer can be converted into an ammeter.
A moving-coil galvanometer has a resistance of 100 and a full-scale deflection of 5.00 mA. Calculate the size of the resistor required to convert it into an ammeter with a full-scale deflection of 1.00 A.
Æ What is the effective resistance of the ammeter?
Why does the magnet in a moving-coil galvanometer have curved pole faces? Q3 Explain the difference between intrinsic and extrinsic conduction in semiconductors.
Draw a labelled diagram of a p-n junction. Explain how a p-n diode can be used to convert a.c. to d.c. Draw a diagram of a circuit used to get a smooth d.c. output from an a.c. source.
Explain why a light-emitting diode (LED) emits light when a suitable forward bias is applied to it. Give two ways in which a photodiode differs from an LED and give a use for a photodiode.
(9) (6) (5)
(12) (9) (9) (9) (9) (8)
Q4 The transistor was one of the most important inventions of the twentieth century. Describe the underlined term. (4)
Name the three currents flowing in a transistor and state the relationship between them. (9)
Fig 24.27 shows the circuit of a voltage amplifier. Explain how the circuit operates. (12)
Draw a sketch of the input and output voltages, using the same axes and scales when a small varying voltage is applied to the amplifier. (9) A NOT gate is a voltage inverter.
Draw a circuit diagram to show how a transistor can be used as a voltage inverter. (12) Give the truth table of an AND gate. (10)
