Unit of Current Important Questions

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Unit of Current is Ampere. It is denoted by the symbol A. It is also denoted by the shorted form ‘amps’. One ampere is equal to 6.241509074 × 10¹⁸ electrons worth of charge moving past a point in a second. The charge of an electron e is 1.602 176634 ×10^-19 Coulomb. Unit of current is an SI unit and thus used universally for all current measurements. This topic is under Class 12 Chapter 3 Current Electricity.

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Important Questions on Unit of Current

Ques 1. Define Ampere. (2 marks)

Ans. Ampere is the flow of electric charge at the rate of 1 coulomb per second. Ampere is denoted by the symbol A.

Ques 2. What are the uses of Ammeter? (2 marks)

Ans. Ammeter is a device used to measure electric current. It can measure both alternating current and direct current. It is connected in series inorder to measure the current.

Ques 3. Calculate the resistance of a light bulb if its voltage is 10V and carries a current 5A. (3 marks)

Ans: By Ohm’s law,

V = IR

R = V/I

R =10/5

R = 2 Ohms

Ques 4. A battery connected to a 0.8 amp light bulb can effectively store 5,500 C of charge when fully charged. How long will the battery last before going dead if the light is left on? (3 marks)

Ans. We know that

I = Q/t

t = Q/I

= 5500/0.8

= 6875 sec

= 1.91 hours

Ques 5. A light bulb draws 300mA of current when its voltage is 240V. Calculate the resistance. (3 marks)

Ans. I = 300mA = 300/1000 A

= 0.3 A

V = 240V

By Ohm’s law,

V = IR

R = V/I

R = 240/0.3

R = 800 Ohms

Ques 6. Calculate the current passing through an electrical device of resistance 10 ohms and voltage 100V. (3 marks)

Ans. R = 10 ohms

V = 100V

By Ohm’s law,

V = IR

I = V/R

= 100/10

= 10 Ampere

Ques 7. What is electric current? (2 marks)

Ans. The rate of flow of charges through a conductor with a defined potential difference is called electric current. If Q is the charge flowing through a conductor in a time interval of t, then current I is given by,

I = Q/t

Ques 8. If current flowing through a conductor for 6 minutes id 0.6A, find the charge. (3 marks)

Ans. We know that,

I = Q/t

Q = ?

I = 0.6A

t = 6 min = 360 sec

Q = Ixt

= 0.6 x 360

= 216 C

Ques 9. If 2A current flows for 5 minutes, the amount of charge flowing through the conductor is? (3 marks)

Ans. We know that,

I = Q/t

I = 2A

t = 5 min = 300 sec

Q = Ixt

= 2 x 300

= 600C

Ques 10. If 600C charge flows for 5 minutes, calculate the current flowing through the conductor. (3 marks)

Ans. We know that,

I = Q/t

I = ?

Q = 600C

t = 5 min = 300 sec

I = Q/t

= 600/300

= 2A

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CBSE CLASS XII Related Questions

1.
Two metal spheres of radii $r_1$ and $r_2$ ($> r_1$) having charges $q_1$ and $q_2$ respectively kept in air, are brought in contact. Which of the following statements is not correct ?
- The total charge of the two spheres is conserved.
- Both spheres attain the same potential.
- The final potential of the system equals $\frac{1}{4\pi\epsilon_0} \frac{(q_1 + q_2)}{(r_1 + r_2)}$
- The final potential of the system equals $\frac{1}{4\pi\epsilon_0} \frac{(q_1 + q_2) (r_1 + r_2)}{r_1 r_2}$
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2.
Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.
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3.
The resistance of a metal wire at $ 20^\circ \text{C} $ is $ 1.05 \, \Omega $ and at $ 100^\circ \text{C} $ is $ 1.38 \, \Omega $. Determine the temperature coefficient of resistivity of this metal.
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4.
Consider the nuclear reaction $ X \to Y + Z $. Let $ M_x $, $ M_y $, and $ M_z $ be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?
- $ (M_x - M_z)<M_y $
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5.
Read the following paragraph and answer the questions that follow.
In an experiment with convex lens of focal length f, the screen is fixed at a distance D from the object. A student slowly moves the lens away from the object towards the screen and finds that she is able to form sharp image of the object for two positions of the lens. The distance between these two positions of the lens is d.
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With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.
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Unit of Current Important Questions

Important Questions on Unit of Current

CBSE CLASS XII Related Questions

1.
Two metal spheres of radii $r_1$ and $r_2$ ($> r_1$) having charges $q_1$ and $q_2$ respectively kept in air, are brought in contact. Which of the following statements is not correct ?

2.
Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

3.
The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

4.
Consider the nuclear reaction \( X \to Y + Z \). Let \( M_x \), \( M_y \), and \( M_z \) be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?

6.
With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

Unit of Current Important Questions

Important Questions on Unit of Current

CBSE CLASS XII Related Questions

1.Two metal spheres of radii $r_1$ and $r_2$ ($> r_1$) having charges $q_1$ and $q_2$ respectively kept in air, are brought in contact. Which of the following statements is not correct ?

2.Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

3. The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

4.Consider the nuclear reaction \( X \to Y + Z \). Let \( M_x \), \( M_y \), and \( M_z \) be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?

6.With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

1.
Two metal spheres of radii $r_1$ and $r_2$ ($> r_1$) having charges $q_1$ and $q_2$ respectively kept in air, are brought in contact. Which of the following statements is not correct ?

2.
Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

3.
The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

4.
Consider the nuclear reaction \( X \to Y + Z \). Let \( M_x \), \( M_y \), and \( M_z \) be the masses of the three nuclei X, Y, and Z respectively. Then which of the following relations hold true?

6.
With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.