Physics Paper 2 WASSCE (PC), 2019

 

Question 11

(a) What is an electric field?

 

(b) State two differences between gravitational potential and gravitational field strength.

 

(c) Study the circuit diagram below and answer the questions that follow.
Calculate the:
(i) equivalent capacitance;
(ii) total energy stored.

 

(d) An alternating voltage V = 25 sin 100 πt is applied to a pure capacitive circuit. If the maximum current in the circuit is 20 mA, calculate the:
(i) capacitive reactance;
(ii) capacitance of the capacitor.

 

(e) What is a phasor diagram?

Observation

Part (a): Candidates performance was below average.
Part (b): Candidates performance was below average.
Part (c) Performance was fair. Many candidates correctly
Part (d): Performance was fair. Most candidates were unable to explain the phasor diagram.
The expected answer is :

11(a)Electric field
A region/space around a charged particle/body where electric force is experienced/felt.

 

(b) Differences between gravitational potential and gravitational field strength

Gravitational potential

Gravitational field strength

Work done per unit mass

Force per unit mass

Obeys the inverse law

Obeys the inverse square law

Unit is J kg-1/V

Unit is N kg-1/Vm-1

It is a scalar quantity

It is a vector quantity

 

(ci) Calculation of equivalent capacitance

 

(ii) Calculation of total energy stored
(di) Calculation of capacitive reactance

 

(ii) Calculation of capacitance of capacitor
(e) Phasor diagram
A vector diagram showing the relationship between the current and voltage and the phase difference between them.