Magnetic field intensity H at the centre of a circular loop of radius r carrying current I emu is
Which of the following materials is the best conductor of electricity ?
Platinum
Gold
Silicon
Copper
A junction diode has a resistance of 25 Ω when forward biased and 2500 Ω when reverse biased. The current in the diode, for the arrangement shown will be
If the electron in a hydrogen atom jumps from an orbit with level n1 = 2 to an orbit with level n2 = 1 the emitted radiation has a wavelength given by
What is the particle X in the following nuclear reaction ?
Electron
Proton
Photon
Neutron
D.
Neutron
Comparing sum of mass numbers and atomic numbers on both sides, we get
A = 1, Z = 0
Hence, X represents (neutron)
The distance between an object and a divergent lens is m times the focal length of the lens. The linear magnification produced by the lens is
m
m + 1
A 2.0 cm object is placed 15 cm in front of a concave mirror of focal length 10 cm. What is the size and nature of the image ?
4 cm, real
4 cm, virtual
1.0 cm, real
None of these
A beam of monochromatic blue light of wavelength 4200 in air travels in water of refractive index 4/3. Its wavelength in water will be.
4200
5800
4150
3150
Two identical light waves, propagating in the same direction, have a phase difference 6. After they superpose the intensity of the resulting wave will be proportional to