23554.Infrared radiation was discovered in 1800 by
William Wollaston
William Herschel
Wilhelm Röntgen
Thomas Young
23555.In electromagnetic wave, according to Maxwell, changing electric field gives
stationary magnetic field
conduction current
eddy current
displacement current
23556.The magnetic field in a travelling electromagnetic wave has a peak value of 20 nT. The peak value of electric field strength is :
3 V/m
6 V/m
9 V/m
12 V/m
23557.Absorption of X–Rays is maximum in which one of the following material sheets of the same thickness?
Cu
Au
Be
Pb
23558.Electromagnetic wave consists of periodically oscillating electric and magnetic vectors ______.
in mutually perpendicular planes but vibrating with a phase difference of $π$
in mutually perpendicular planes but vibrating with a phase difference of $π$/2
in randomly oriented planes but vibrating in phase
in mutually perpendicular planes but vibrating in phase
23559.The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than 2480 nm is incident on it. The band gap in (eV) for the semiconductor is
1.1 eV
2.5 eV
0.5 eV
0.7 eV
23560.The capacity of a parallel plate air capacitor is 2 μF and voltage between the plates is changing at the rate of 3 V/S. The displacement current in the capacitor is
2 μF
3 μF
5 μF
6 μF
23561.Assertion : The energy (E) and momentum (p) of a photon are related by p = E/c.
Reason : The photon behaves like a particle.
Reason : The photon behaves like a particle.
both assertion and reason are true and reason is the correct explanation of assertion.
both assertion and reason are true but reason is not the correct explanation of assertion.
assertion is true but reason is false.
assertion and reason are false.
23562.Arrange the following electromagnetic radiations per quantum in the order of increasing energy: A : Blue light
B : Yellow light
C : X–ray
D : Radiowave
B : Yellow light
C : X–ray
D : Radiowave
A, B, D, C
C, A, B, D
B, A, D, C
D, B, A, C