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
D.
decreasing the potential difference between the anode and filament
In the Davisson and Germer experiment, the velocity of the electron emitted from the electron gun can be increased by increasing 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
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)