In photoelectric effect, electrons will leave the metal surface when illuminated by light of appropriate frequency if the photon energy is

• A. greater than the work function
• B. less than the work function
• C. equal to the work function
• D. equal to the maximium kinetic energy of the electron

The gravitational force of the moon is one-sixth that of the earth. If a body weighs 6.0N on the moon. Calculate its weight on the earth

• A. 36.0N
• B. 12.0N
• C. 6.0N
• D. 2.0N

A parallel plate capacitor has a common plate area of 5 x 10\(^{-8}\)m2 and plate separation of 2 x 10\(^3\)m, Assuming free space,

What is the capacitance? [\(\varepsilon\)o = 9.0 X 10-\(^{-12}\)C2N-1m-2]

• A. 2.25 x 10^-17F
• B. 4.50 x 10^-17F
• C. 2.25 x 10^-16F
• D. 4.50 x 10^-16F

An electron of mass 9.1 x 10\(^{-31}\) kg moves with a speed of 2.0 x 10\(^6\) ms\(^{-1}\) round the nucleus of an atom in a Circular path of radius 6.1 x 10\(^{11}\) m. Calculate the centripetal force acting on the electron.

• A. 7.7 x 10\(^{47}\) N
• B. 6.0 x 10\(^{-8}\)N
• C. 3.0 x 10\(^{-14}\)N
• D. 1.3 x 10\(^{-26}\)N

The following statements are advantages of a solid dielectric material between the plates of a capacitor except that

• A. the maximum potential difference the capacitor can withstand is increased.
• B. it increases the electrical conduction of the capacitor.
• C. the capacitance of the capacitor of given dimensions is much greater than that of the plates in a vacuum.
• D. it keeps the plates at a fixed separation.