K.C.S.E Physics Q & A - MODEL 2015PP2QN17

K.C.S.E Physics Q & A - MODEL 2015PP2QN17

​(a) State three factors that affect the capacitance of a parallel plate capacitor. 
(b) Figure 5 shows the circuit used to charge a capacitor C

​(i) State what would be observed on the following when the switch is closed:
(I) the milliammeter; 
(II) the voltmeter; 
(ii) Explain how the capacitor gets charged. 
(iii) State the purpose of the resistor R. 
(iv) On the axes provided, sketch the graph of voltage (V) against time (t)

answers

​(a) distance of separation between plates
area of overlap of plates
type of dielectric between plates 
(b) (i) (I) Current rises to maximum and then drops to zero 
(II) Potential difference between the plates increases to a maximum 
(ii) Negative charges flow from the negative terminal of the battery to one plate of the capacitor. Negative charges flow from the other plate of the capacitor to the positive terminal of the cell hence equal positive and negative
charges gather on the plates, opposing further flow of electrons when fullycharged  
(iii) Resistor - to slow down the charging process so that current and voltage are is observed.