Physics
Current electricity
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#33 The current in a conductor is due to
A) Drift of electrons
B) Drift of protons
C) Drift of ions
D) All of these
#34 The number density of free electrons in a metal is of the order of
A) $10^{28} m^{-3}$
B) $10^{24} m^{-3}$
C) $10^{20} m^{-3}$
D) $10^{16} m^{-3}$
#35 The resistivity of a conductor increases with temperature because
A) Number density of free electrons decreases
B) Relaxation time decreases
C) Both A and B
D) Neither A nor B
#36 The resistivity of a semiconductor decreases with temperature because
A) Number density of charge carriers increases
B) Relaxation time increases
C) Both A and B
D) Neither A nor B
#37 The color code for a resistor of resistance 1 kO with 5% tolerance is
A) Brown, black, red, gold
B) Brown, black, orange, gold
C) Brown, black, red, silver
D) Brown, black, orange, silver
#38 The color code for a resistor of resistance 10 MO with 10% tolerance is
A) Brown, black, blue, silver
B) Brown, black, green, silver
C) Brown, black, blue, gold
D) Brown, black, green, gold
#39 The value of resistance using color code: yellow, violet, orange, gold is
A) 47 kO ± 5%
B) 47 kO ± 10%
C) 4.7 kO ± 5%
D) 4.7 kO ± 10%
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