The current i in a coil varies with time as shown in the figure. The variation of induced emf with time would be

An AC voltage is applied to a resistance R and an inductor L in series. If R and the inductive reactance are both equal to 3Ω, the phase difference between the applied voltage and the current in the circuit is 

• π/4

• π/2

• zero

• zero

The decreasing order of wavelength of infrared, microwave, ultraviolet and gamma rays is

• gamma rays, ultraviolet, infrared, microwaves

• microwaves, gamma rays, infrared, ultraviolet

• infrared, microwave, ultraviolet, gamma rays.

• infrared, microwave, ultraviolet, gamma rays.

A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected in the region such that its velocity is pointed along direction of fields, then the electron

• speed will decrease

• speed will increase

• will turn towards the left of the direction of motion

• will turn towards the left of the direction of motion

In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by

• Increasing the filament current

• decreasing the filament current

• decreasing the potential difference between the anode and filament

• decreasing the potential difference between the anode and filament

A radioactive nucleus of mass M emits a photon of frequency v and the nucleus recoils.The recoil energy will be

• h²v² / 2Mc²

• zero

• hv

• hv

The power obtained in a reactor using U²³⁵ disintegration is  1000kW. The mass decay of U²³⁵ per hour is

• 20 μg

• 40 μg

• 1 μg

• 1 μg

The half - life of a radioactive isotope X is 50 yr. It decays to another element Y which is stable. The two elements X and Y were found to be in the ratio of 1: 15 in a sample of a given rock. The age of the rock was estimated to be

• 200 yr

• 250 yr

• 100 yr

• 100 yr

In photoelectric emission process from a metal of work function 1.8 eV, the kinetic energy of most energetic electrons is 0.5 eV. The corresponding  stopping potential is

• 1.3 V

• 0.5 V

• 2.3 V 

• 2.3 V 

40.

Symbolic representation of four logic gates are shown as,




Pick out which ones are for AND, NAND and NOT gates, respectively.

• (iii), (ii)  and (i)

• (iii), (ii) and (i)

• (ii), (iv), and (iii)

• (ii), (iv), and (iii)