12th class (Fsc) Physics unit 2 MCQs
26. Temperature co-efficient of resistance (∞) is equal:
a. R1 – Ro / Ro ∆ t
b. R1 + Ro / Ro ∆ t
c. Ro – R1 / Ro ∆ t
d. None of these
27. When a wire of length ‘ l ’and resistance R is cut into two equal parts then resistivity of each part:
a. Becomes two times
b. Becomes half
c. Becomes four times
d. Remains unchanged
28. Resistivity at a given temperature depends upon:
a. Nature of material of conductor
b. Area of cross section
c. Both length and area
d. Length
29. Temperature co-efficient of resistivity is measured in:
a. k-1
b. Ωk
c. k
d. Ωm
30. What is the resistance of a carbon resistor which has bands brown, black and brown:
a. 10 Ohm
b. 100 Ohm
c. 1.0 Ohm
d. 1000 Ohm
31. What is the colour code for 52 MΩ + 5% resistance:
a. Yellow red blue gold
b. Red green blue gold
c. Green red violet gold
d. Green red blue gold
32. If length of Solenoid is doubled but N same, B inside the Solenoid becomes:
a. One fourth
b. Half
c. Four times
d. Double
33. The thermistors convert the changes of temperature in to:
a. Sound energy
b. Heat energy
c. Electrical energy
d. Light energy
34. The resistance of a conductor L, cross-sectional area ‘A’ and resistivity ‘ ’ is given by:
a. R = PL/A
b. R = P/AL
c. R = PA/L
d. R = PAL
35. Three resistances each of 4Ω are connected to form a triangle, the resistance between any two terminal is:
a. 8/3Ω
b. 4Ω
c. 3/8Ω
d. 12Ω
36. The current through a resistance of 100Ω when connected across a source of 220V is:
a. 2.2 A
b. 22000 A
c. 0.45 A
d. 22 A
37. An ideal current source shall have resistance:
a. Infinite
b. Zero
c. Depends upon requirement
d. Finite but not zero
38. The terminal potential difference of a battery of internal resistance ‘r’ and emf:
a. V = ε – r/l
b. V = ε + lr
c. 1/ ε – r
d. V = ε = lr
39. The substance having negative temperature co-efficient is:
a. Tungsten
b. Carbon
c. Gold
d. Iron
40. Resistance tolerance for gold color is:
a. 20%
b. 50%
c. 5%
d. 30%
41. If fourth band is missing on resistance, its tolerance is:
a. ±15%
b. ±5%
c. ±20%
d. ±10%
42. The thermistors convert changes of temperature into:
a. Heat
b. Light energy
c. Sound
d. Electric voltage
43. In carbon resistors, the value of Blue color is:
a. 8
b. 7
c. 9
d. 6
44. If the resistance of 500Ω have fourth band of silver color then its upper maximum
resistance will be :
a. 450Ω
b. 600Ω
c. 400Ω
d. 550Ω
45. Resistance tolerance of silver band is:
a. 7%
b. 10%
c. 5%
d. 6%
46. Which one or the following DUIDS has the least resistance?
a. 500 watts
b. 100 watts
c. 1000 watts
d. 200 watts
47. The maximum power (pout) is delivered to a load resistance R, when the internal resistance of the source is:
a. r = o
b. r = a
c. = R/4
d. r = R
48. A rheostat can operates as:
a. Oscillator
b. Amplifier
c. Transformer
d. Potential divider
49. Heat sensitive resistors are called:
a. Thermistors
b. Resistors
c. Inductors
d. Capacitor
50. Color codes are used to calculate the:
a. Potential difference
b. Nature of resistor
c. Current
d. Numerical value of resistance