Atoms — Physics STD 12 Science — Question

A free electron is placed in the path of a plane electromagnetic wave. The electron will start moving:

Consider a current carrying wire (current I) in the shape of a circle. Note that as the current progresses along the wire, the direction of j (current density) changes in an exact manner, while the current I remain unaffected. The agent that is essentially responsible for is:

In an insulator, the forbidden energy gap between valence band and conduction band is of the following order :

A potential difference of 300 volts is applied to a combination of 2.0mF and 8.0mF capacitors connected in series. The charge on the 2.0mF capacitor is

(a) 2.4

(b) 4.8

(c) 7.2

(d) 9.6

The k line of singly ionised calcium has a wavelength of 393.3 nm as measured on earth. In the spectrum of one of the observed galaxies, this spectral line is located at 401.8 nm. The speed with which the galaxy is moving away from us, will be

(a) 6480 km/s

(b) 3240 km/s

(c) 4240 km/sec

(d)  None of these

The amplitude of the magnetic field of a harmonic electromagnetic wave in vacuum is B_0​ = 510nT. The amplitude of the electric field part of the wave is:

Electric switches and appliances should be tested only with:

In a negative logic the following wave form corresponds to the

(a) 0000000000

(b) 0101101000

(c) 1111111111

(d) 1010010111

As the quantum number increases, the difference of energy between consecutive energy levels?

Dark lines on solar spectrum are due to

(a) Lack of certain elements

(b) Black body radiation

(c) Absorption of certain wavelengths by outer layers

(d) Scattering