Explanation:
As shown in the image, insulators have a very large forbidden gap. Their conduction band is empty, thus they cannot conduct electricity under normal room temperature and pressure conditions. The valence band is full.
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Light of wavelength 4000 Å falls on a photosensitive metal and a negative 2V potential stops the emitted electrons. The work function of the material (in eV) is approximately (h = 6.6 
|
(a) 1.1 |
(b) 2.0 |
(c) 2.2 |
(d) 3.1 |
In a plano-convex lens the radius of curvature of the convex lens is 10 cm. If the plane side is polished, then the focal length will be (Refractive index = 1.5)
|
(a) 10.5 cm |
(b) 10 cm |
(c) 5.5 cm |
(d) 5 cm |
Every series of hydrogen spectrum has an upper and lower limit in wavelength. The spectral series which has an upper limit of wavelength equal to 18752 Å is (Rydberg constant 
per metre)
|
(a) Balmer series |
(b) Lyman series |
(c) Paschen series |
(d) Pfund series |
Two charges each equal to 2μC are 0.5m apart. If both of them exist inside vacuum, then the force between them is
|
(a) 1.89 N |
(b) 2.44 N |
(c) 0.144 N |
(d) 3.144 N |