Li nucleus has three protons and four neutrons. Mass of lithium nucleus is 7.016005 amu. Mass of proton is 1.007277 amu and mass of neutron is 1.008665 amu. Mass defect for lithium nucleus in amu is
0.04048 amu
0.04050 amu
0.04052 amu
0.04055 amu
Time taken by sunlight to pass through a window of thickness 4 mm whose refractive index is is
2 × 10-4 s
2 × 104 s
2 × 10-11 s
2 × 1011 s
Two thin lenses of focal length 20 cm and 25 cm are in contact. The effective power of the combination is
4.5 D
18 D
45 D
9 D
The magnification of the image when an object is placed at a distance x from the principal focus of a mirror of focal length f is
In the Young's double slit experiment, the central maxima is observed to be I0. If one of the slits is covered, then the intensity at the central maxima will become
The ratio of the de-Broglie wavelength of an -particle and a proton of same kinetic energy is
1 : 2
1 : 1
1 :
4 : 1
Which of the following is not conserved in nuclear reaction ?
Total energy
Mass number
Charge number
Number of fundamental particles
The number of -particles and β-particles respectively emitted in the reaction 88A196 → 78B164 are
8 and 8
8 and 6
6 and 8
6 and 6
The counting rate observed from a radioactive source at t = 0 was 1600 count/s and at t = 8 s it was 100 counts/s. The counting rate observed as counts per second at t = 6 s, will be
400
300
250
200
D.
200
If n1 and n2 are the refractive indices of the core and the cladding respectively of an optic fibre, then
n1 = n2
n1 < n2
n2 < n1
n2 = 2 n1