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1.0.0
MCQ
41. What will be the current in 2 seconds from a wire of having 10 mC charge flow and 2.5mm cross sectional area?
25mA
5mA
20mA
4mA
42. If a galvanometer is open circuited in a balanced Wheatstone bridge, the current in various resistors of Wheatstone bridge will---
Increase
Decrease
Not change
Cannot say anything
43. The total resistance of circuit by connecting 50 resistance of 1/4 Ω in parallel is---
50/4Ω
200Ω
4/50Ω
1/200Ω
44. Electrical appliances are connected in parallel because it-
Is a simple circuit
Draws less current
Results in reduced power loss
Makes the operation of appliances independent of each other
45. A wire has a resistance of 122. It is bent in the form of a circle. The effective resistance between the two points on any diameter of the circle is--
6Ω
12Ω
3Ω
24Ω
46. A 50V battery is connected across 10Ω resistor. The current is 4.5 A. The internal resistance of the battery is-
zero
0.5Ω
5Ω
1.1Ω
47. Two resistors of 18Ω and 5Ω are connected in series to a 230 volt supply. The current is-
12A
10A
10.5A
9.5A
48. A 40W bulb is connected in parallel with room heater. What will happen if we turn off bulb?
Heater output will increase
Heater output will decrease
Heater output will remains same
None of the above
ব্যাখ্যা: In parallel connection, the voltage across the element is constant. Therefore, the voltage across heater remains same.
49. The true statement for a series and a parallel de circuit is--
powers are additive
current are additive
element have individual current
voltage are additive
ব্যাখ্যা: Powers are additive in both series and Parrallel. Currents are additive in parallel circuits whereas voltages are additive in series circuit.
50. The internal resistance of a cell of e.m.f 2V is 0.1Ω It is connected to a resistance of 3.9Ω. The voltage across the cell is-
0.5V
1.9V
1.95V
2V
51. The resistance of each arm of Wheatstone bridge is 10 Ω. A resistance of 10Ω is connected in series with the galvanometer. The equivalent resistance across the battery will be-
40 Ω
20 Ω
30 Ω
10 Ω
52. Permeability in a magnetic circuit corresponds to--in electric circuit.
conductivity
conductance
resistivity
resistance
53. Kirchhoff's voltage law deals with—
Conversation of energy
Conversation of momentum
Conversation of charge
Conversation of angular momentum
54. What happens if an electric bulb rated at 220V is connected to 220V, 5 Hz ac source? The bulb-
does not glow
fuses
glows continuously
glows intermittently
ব্যাখ্যাঃ When you give 5Hz supply, frequency is too low. Normally when 50 Hz (50 times a second AC is given, it will get max volts twice in each cycle, that is it gets varing voltage from 0 to 220'a hundred times a second, in negative and positive cycles), the white hot blulb filament has no time to cool. Hence it appears to us as glowing continuously. But when you drastically reduce to 5 Hz it has times to cool off and again get white when hot. You will observe the blub will flash at rate of 10 times per seconde
55. Kirchhoff's current law at a junction deals with-
Conversation of energy
Conversation of momentum
Conversation of charge
Conversation of angular momentum
ব্যাখ্যা: Kirchhoff's Current Law (KCL) is Kirchhoff's first law deals with the conservation of charge entering and leaving a junciton
56. What will be the internal resistance of cell, if it supplies 0.9A current through 2Ω resistor and 0.3A current through 7Ωresistor?
0.9Ω
1.2Ω
0.5Ω
1Ω
57. An external resistance R is connected to a cell of internal resistance r. The maximum current flows in the external resistance when-
R<r
R=r
R>r
None of the above
58. Two equal resistances are connected in series across a certain supply. If the resistances are now connected in parallel, the power produced will become-
two-times
four times
one-half
one-fourth
ব্যাখ্যাঃ if two equal resistance connected in series across a certain supply are now connected in parallel across the same supply, the power produced will be four times that of series connection.
59. Three resistance 14.5Ω, 25.5Ω and 60Ω are connected in series across 200V. What will be the voltage drop across 14.5Ω?
29V
14V
13.5V
18V
60. Suppose, double the voltage in a simple de circuit and cut the resistance in half, then the current will-
Become four times as great
Become twice as great
Stay the same as it was before
Become half as great