CBSE
Temperature of a piece of silicon is raised from 27°C to 100°C, then its conductivity
increases
decreases
remains same
becomes zero
A battery of four cells in series,each having an emf of 1 .4 V and an internal resistance of 2 is to be used to charge a small 2 V accumulator of negligible internal resistance. What is the charging current?
0.1 A
0.2 A
0.3 A
0.45 A
The length of a wire of a potentiometer is 100 cm, and the emf of its stand and cell is E volt. It is employed to measure the emf of a battery whose internal resistance is 0.52 Ω.1fthe balance point is obtained at l= 30 cm from the positive end, the emf of the battery is
Work of invertor is
to change AC into DC
to change DC into AC
to regulate voltage
None of the above
The material of wire of potentiometer is made of
copper
steel
manganin
aluminium
A voltmeter of resistance 998 is connected across a cell of emf 2V and internal resistance 2. The potential difference across the voltmeter is
1.99 V
3.5 V
5 V
6 V
A potential difference V is applied at the ends of a copper wire of length l and diameter d. On doubling only d, drift velocity
becomes two times
becomes half
does not change
becomes one-fourth
A small current carrying loop acts as a small magnet. The area of the loop is A and magnetic moment is M. The current in the loop will be
MA
A2M
The electrical resistivity of a sample
is proportional to its length
is proportional to the area of cross-section
is inversely proportional to the length
neither depends on the length nor on the area of cross-section
An ammeter reads upto 1 A. Its internal resistance is 0.81 Ω. To increase the range to 10 A, the value of the required shunt is
0.03 Ω
0.3 Ω
0.9 Ω
0.09 Ω