Physics Past Questions and Answers

An isolated metal sphere of radius R, carrying an electric charge Q, is situated in the medium of relative permitivity, E_r. A test charge is placed at a point p, distance r from the surface of the sphere. Let E_o represent the permitivity of free space. The magnitude of the electric field intensity at P is given by the expression

A \(\frac{Q}{4 \pi E_o E_r r^2}\)
B \(\frac{Q}{4 \pi E_o E_r(R + r)^2}\)
C \(\frac{Q}{4 \pi E_o E_r(R - r)^2}\)
D \(\frac{Q}{4 \pi E_o E_rR^2}\)

Question 1307:

A resistor of resistance R is connected to a battery of negligible internal resistance. If a siilar resistor is connected in series with it the

A Effective resistance of the circuit is halved
B Total power dissipated is doubled
C Total current in the circuit is halved
D Terminal voltage is halved

Question 1308:

A cell of e.m.f. 1.5V is connected in series with a resistor of resistance 3.0\(\Omega\). A voltmeter connected across the cell registers 0.9V. Calculate the internal resistance of the cell

A 2.0\(\Omega\).
B 3.0\(\Omega\).
C 5.0\(\Omega\).
D 6.0\(\Omega\).

Question 1309:

A wire of resistivity 4.40 x 10^-5\(\Omega\) cm has a cross sectional area of 7.50 x 10^-4 cm². Calculate the length of the wire that will be required to make a 4.0\(\Omega\) resistor

A 82.50 cm
B 68.18cm
C 15.90cm
D 11.95cm

Question 1310:

A battery of e.m.f. 12.0V and internal resistance0.5\(\Omega\) is connected to 1.5\(\Omega\) and 4.0\(\Omega\) series resistor. Calculate the terminal voltage of the battery.

A 13.0V
B 11.0V
C 3.0V
D 1.0V