Physics Past Questions and Answers

If the distance from a point source of sound is doubled, by what factor does the intensity decrease?

A 4.00
B 2.00
C 0.50
D 0.25

Question 22:

A 2000W electric heater is used to heat a metal object of mass 5kg initially at 10oC. If a temperature rise of 30oC is obtained after 10min, the heat capacity of the material is

A 6.0 x 10⁴J^oC^-1
B 4.0 x 10⁴J^oC^-1
C 1.2 x 10⁴J^oC^-1
D 8.0 x 10⁴J^oC^-1

Question 23:

If 1.2 x 10⁶J of heat energy is given off in 1 sec from a vessel maintained at a temperature gradient of 30Km^-1, the surface area of the vessel is

A 1.0 x 10²m²
B 9. 0 x 10²m²
C 1.0 x 10³m²
D 9.0 x 10⁴m²

Question 24:

A positive charged rod X is brought near as uncharged metal sphere Y and is then touched by a finger with X still in place. When the finger is removed, the result is that y has

A No charge and a zero potential
B A positive charge and zero potential
C A negative charge and positive potential
D A negative charge and a negative potential

Question 25:

In the diagram above, if each of the resistors can dissipate a maximum of 18W without becoming excessively heated, what is the maximum power the circuit can dissipate?

A 27W
B 18W
C 9W
D 5W