A) 1 watt per square metre
B) 1 kilowatt per square metre
C) 1 megawatt per square metre
D) None of these

A) Secondary cells have limited life
B) In the primary cell the energy conversion is accompanied by changes in cell composition which are reversible
C) In a secondary cell, the chemical reactions are reversible
D) In a secondary cell, during charge, lead sulphate and water are formed

A) All four
B) (1) and (2)
C) (2) and (4)
D) (1) and (3)

A) 2, 4
B) 1, 2
C) 2, 3
D) 1, 3

A) The electrical conduction is by electrons and holes
B) With rise in temperature, the conductivity decreases
C) The conduction band is empty
D) There is a small energy gap between the two bands

A) With increasing temperature the density of electron hole pairs increases
B) In intrinsic  germanium the resistivity increases 6% per degree rise in temperature
C) At low temperature, well above 0 K, electrons move into the valence bond
D) Hole along with electrons carry current in the conduction band

A) The hole concentration is less than the electron concentration
B) Electrons are the majority carriers
C) At room temperature the hole concentration equals the acceptor concentration
D) Electron density does not change with temperature

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