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Ampere is the unit of electric current named after the French Physicist and Mathematician Andre-Marie Ampere. We would come across this unit of measurement in the concept of Current Electricity from the latest CBSE Class 12 Physics Syllabus.
Ampere is the unit used to quantify the flowing current in a system. One Ampere is hence defined as the flow of one Coulomb of charge in one second. It is denoted by the letter ‘A’. Thus,
1A = 1C/s = 1 Cs-1
An Ampere can also be expressed as the amount of current produced by the force of one volt which acts through a resistance of one Ohms. In the area through which current flows at any given point if the charge in the moving particles increases, the Ampere value also proportionately increases.
Let us look at some multiple choice questions based on Ampere.
Read More: NCERT Solutions for Class 12 Physics Chapter 3 Current Electricity
Class 12 Ampere MCQs
Ques. The SI Unit of current is _________.
- Coulomb
- Ampere
- Coulomb Second
- None of the above
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Ans. The correct option is B. Ampere
Explanation: Ampere is the SI Unit of electric current. One Ampere is the flow of one coulomb of charge in one second.
Ques. Electric current flow is from __________.
- Positive to negative terminal
- Negative to positive terminal
- Both ways
- None of the above
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Ans.The correct option is A. Positive to negative terminal
Explanation: Conventionally the direction of current is taken as opposite to the direction of the flow of electrons. Since electron flow from the negative terminal to the positive terminal of a battery. Therefore, The direction of the current is taken as the positive terminal to the negative terminal.
Ques. One ampere is defined as ___________
- Charge passing per minute
- 1 coulomb of charge flowing per minute
- 1 coulomb of charge flowing per second
- Charge per second
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Ans. The correct option is C. 1 coulomb of charge flowing per second
Explanation: One ampere is defined as the flow of one coulomb of charge in one second.
1A= 1Cs-1
Ques. Current flowing through a circuit is 0.6 A. If the current flow for 6 minutes, what is the amount of electric charge?
- 216 C
- 360 C
- 60 C
- 36 C
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Ans. The correct option is A. 216 C
Explanation: I = 0.6 A
T = 6 min
= 6x60= 360sec
Q = Ixt
= 0.6 x 360
=216 C
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Ques. What is the charge across the cross-section of semiconductor if 2A of electric current flows for 5 minutes?
- 205 C
- 150 C
- 600 C
- 10 C
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Ans. The correct option is C. 600C
Explanation: I = 2A
t = 5 min
=5 x60
=300 s
Q = Ixt
= 2 x 300
600 C
Ques. What is number of electrons passing per second through a conductor with electric current of 1 mA flowing through it?
- 1.6 x 10-16
- 1.6 x 1016
- 6.25 x 1015
- 6.25 x 1017
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Ans. The correct option is C. 6.25 x 1015
Explanation: I = Q/t — (1)
Here,
I = 1 mA
= 1x 10-3 A
t = 1 sec
Total charge passing per second = Q = ne
We know from (1) that Q= I x t
ne = It
e= It/n
= 10-3 x 1/ 1.6 x 10-19
= 6.25 x 1015
Ques. Electric current is measured using ________.
- Ammeter
- Galvanometer
- Potentiometer
- Pressure Gauge
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Ans. The correct option is A. Ammeter
Explanation: The ammeter is the electric device used to measure the electric current flowing through a circuit.
Ques. Property of a conductor that allows current to pass through it is called ___________.
- Resistance
- Inductance
- Conductance
- Reluctance
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Ans. The correct option is C. Conductance
Explanation: Conductance is the property of a material that allows electric current to pass through it.
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Ques. Instrument that detects electric current in a circuit is called ______.
- Rheostat
- Wattmeter
- Ammeter
- Galvanometer
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Ans. The correct option is D. Galvanometer
Explanation: A galvanometer is used to detect the presence of electric current in a circuit. The ammeter measures the electric current value in a circuit.
Ques. Ohm’s Law is not applicable for ___________.
- High voltage Circuits
- Carbon Resistors
- Circuits with low current densities
- Vacuum tubes
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Ans. The correct option is D. Vacuum tubes
Explanation: A vacuum tube is a non-linear circuit whose conductivity keeps altering with temperature, current, and voltage graph. Thus the plot is not a straight line and hence it does not obey Ohm’s Law.
Ques. When electric current passes through a circuit, it produces a ___________ effect.
- Luminous
- Thermal
- Magnetic
- Chemical
- All of the above
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Ans. The correct option is E. All of the above
Explanation: Electric current causes a chemical reaction when it passes through a conducting solution. This is a chemical effect of electric current. When an electric current passes through the bulb. Its filament gets heated and the bulb starts glowing. This is the heating effect and luminous effect of electric current. When electric current is passed through a circuit it produces a magnetic field around it. This is the magnetic effect of electric current.
Ques. When electric current passes through a conductor, the rise in temperature is due to ________
- Release of electrons from parent atoms
- Mutual collision between parent atoms
- Mutual collision between conducting electrons
- Collision between electrons and atoms
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Ans. The correct option is D. Collision between electrons and atoms
Explanation: The ions in the conductors vibrate when the temperature rises. When the temperature is further increased the vibrations become more vigorous in nature. This increases the number of collisions between the free electrons and the ions (atoms).
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