15 Questions
| Attempts: 1900

Questions and Answers

- 1.Given three resistors, how many different combinations of these three resistances can be made
- A.
Three

- B.
Four

- C.
Five

- D.
Six

- 2.In the Bohr’s model of hydrogen atom, the electron moves around the nucleus in circular orbit of radius 5 ⤬ 10
^{–11 }m. Its time period is 1.5 ⤬ 10^{–16}s. The current associated with electron motion is- A.
Zero

- B.
1.6 ⤬ 10

^{–19}A - C.
1.07 ⤬ 10

^{–3}A - D.
0.17 A

- 3.The temperature (T) dependence of resistivity (p) of a semiconductor is represented by
- A.
- B.
- C.
- D.

- 4.Resistance n, each of r Ω, when connected in parallel give an equivalent resistance of R Ω. If these resistances were connected in series, the combination would have a resistance in Ω, equal to
- A.
N

^{2}R - B.
R / n

^{2} - C.
R / n

- D.
NR

- 5.The current in the arm CD of the circuit will be
- A.
I

_{1}+ i_{2} - B.
I

_{2}+ I_{3} - C.
I

_{1}+ i_{3} - D.
I

_{1}– i_{2}+ i_{3}

- 6.The bulbs A, B and C are connected as shown in Figure. The bulbs B and C are identical. If the bulb C is fused,
- A.
Both A and B will glow more brighty,

- B.
Both A and B will glow less brightly,

- C.
A will glow less brightly and B will glow more brightly,

- D.
A will glow more brightly and B will glow less brightly.

- 7.If R
_{1}and R_{2}are the filament resistances of 200 watt and a 100 watt bulb respectively, both designed to run at the same voltage, then- A.
R

_{1}is four times R_{2} - B.
R

_{2}is four times R_{1} - C.
R

_{1}is two times 3R_{2} - D.
R

_{2}is two times R_{1}

- 8.If a high power heater is connected to electric mains, then the bulbs in the house become dim, because there is a
- A.
Current drop

- B.
Potential drop

- C.
No current drop

- D.
No potential drop

- 9.A house wiring supplied with a 220 V supply line is protected by a 6 ampere fuse. The maximum number of 60 W bulbs is parallel that can be turned on is
- A.
11

- B.
22

- C.
33

- D.
66

- 10.An electric heating element consumes 500 W, when connected to a 100 V line. If the line voltage becomes 150V, the power consumed will be:
- A.
500 W

- B.
750 W

- C.
1000 W

- D.
1125 W

- 11.A 100 W bulb B
_{1}and two 60 W bulb B_{2}and B3 are connected to a 250V source as shown in the Figure. Now W_{1}, W_{2}and W_{3}are the output powers of the bulbs B_{1}, B_{2}and B_{3}respectively. Then- A.
W

_{1}> W_{2}= W_{3} - B.
W

_{1}< W_{2}= W_{3} - C.
W

_{1}< W_{2}< W_{3} - D.
W

_{1}> W_{2}= W_{3}

- 12.In a copper voltameter, mass deposited in thirty seconds is m grams. If the time current graph is as shown in figure. E.C.E. of copper is (current in milli ampere)
- A.
0.1 m

- B.
0.5 m

- C.
0.6 m

- D.
M

- 13.Consider the following two statements (i) Free-electro density is different in different metals. (ii) Free-electro density in a metal depends on temperature. Seebeck effect is caused
- A.
Due to (i) but not due to (ii)

- B.
Due to (ii) but not due (i)

- C.
Due to both (i) and (ii)

- D.
Neither due to (i) nor due to (ii)

- 14.If the electric current in a lamp decreases by 5 %, then the power output decreases by:
- A.
2.5%

- B.
5%

- C.
10%

- D.
20%

- 15.The thermo e.m.f. of a thermo couple varies with the temperature of the hot junction as E = a 𝜃 + b 𝜃
^{2}in bolts where the ratio a/b is 700°C. If the cold temperature is kept at 0°C, then the neutral temperature is- A.
700°C

- B.
350°C

- C.
1400°C

- D.
No neutral temperature is possible for this thermocouple

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