Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R :

Assertion A : The photoelectric effect does not takes place, if the energy of the incident radiation is less than the work function of a metal.

Reason R : Kinetic energy of the photoelectrons is zero, if the energy of the incident radiation is equal to the work function of a metal.

In the light of the above statements, choose the most appropriate answer from the options given below.

A particle of mass 500 gm is moving in a straight line with velocity v = b x^5/2. The work done by the net force during its displacement from x = 0 to x = 4 m is : (Take b = 0.25 m^$$-$$3/2 s^$$-$$1).

A charge particle moves along circular path in a uniform magnetic field in a cyclotron. The kinetic energy of the charge particle increases to 4 times its initial value. What will be the ratio of new radius to the original radius of circular path of the charge particle :

For a series LCR circuit, I vs $$\omega$$ curve is shown :

(a) To the left of $$\omega$$_r, the circuit is mainly capacitive.

(b) To the left of $$\omega$$_r, the circuit is mainly inductive.

(c) At $$\omega$$_r, impedance of the circuit is equal to the resistance of the circuit.

(d) At $$\omega$$_r, impedance of the circuit is 0.

Choose the most appropriate answer from the options given below :