Physics - 27
131. In a p-type semiconductor, which is the main carrier of electricity?
(A) Electrons
(B) Negative Ions
(C) Positive holes
(D) Positive Ions
(A) Electrons
(B) Negative Ions
(C) Positive holes
(D) Positive Ions
Correct Answer: [C] Positive holes.
132. The blue color of the sky is due to
(A) Reflection
(B) Dispersal
(C) Scattering
(D) Refraction
(A) Reflection
(B) Dispersal
(C) Scattering
(D) Refraction
Correct Answer: [C] Scattering.
133. Sound waves in air are
(A) Electromagnetic
(B) Polarized
(C) Transverse
(D) Longitudinal
(A) Electromagnetic
(B) Polarized
(C) Transverse
(D) Longitudinal
Correct Answer: [D] Longitudinal.
134. Red is used as a danger signal because
(A) red colour is easily available.
(B) red colour is soothing for the eye.
(C) blood is red.
(D) red light is scattered least by the air molecules
(A) red colour is easily available.
(B) red colour is soothing for the eye.
(C) blood is red.
(D) red light is scattered least by the air molecules
Correct Answer: [D] red light is scattered least by the air molecules.
135. A. C is converted to D.C. by
(A) Transformer
(B) Motor
(C) Rectifier
(D) Dynamo
(A) Transformer
(B) Motor
(C) Rectifier
(D) Dynamo
Correct Answer: [C] Rectifier.
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