Unit of Resistance Important Questions

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Resistance can be defined as a physical property of a material in which, the material can resist the flow of electricity. The resistance mostly depends upon the physical dimensions, composition, and temperature of the material. Resistance is denoted by the letter ‘R’. The SI unit of resistance is Ohm.

Important Questions On Unit Of Resistance

Ques. What is the SI unit of resistance? (1 Mark)

Ans. The SI unit of resistance is Ohm.

Ques. Define Resistance. (1 Mark)

Ans. Resistance can be defined as a physical property of a material in which, the material can resist the flow of electricity. The resistance mostly depends upon the physical dimensions, composition, and temperature of the material. Resistance is denoted by the letter ‘R’. The SI unit of resistance is Ohm.

Ques. Define the unit of resistance. (1 Mark)

Ans. The SI unit of resistance Ohm is the resistance of a conductor when a current of 1 A flows through it because of a potential difference of 1 V.

Ques. Is resistance and resistivity different term? (1.5 Marks)

Ans. The resistance and resistivity quantify the number of difficulties provided by a material to the flow of electricity. The resistance between the ends of a wire is the total ratio of the potential differences between the two points to the current flowing through the conductor.

The resistivity of a material is defined as the resistance of two units i.e., unit length and unit cross-section of that material. Hence, resistivity is measured in terms of Ohm-meter.

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Ques. What is the dimension of a unit of resistance? (1 Mark)

Ans. The dimension of a unit of the formula is [M] [L2][T-3][1-2]

Ques. Why is the resistance of the voltmeter high? (2 Marks)

Ans. The voltmeter has high resistance to avoid the effects of loading. When the resistance of the voltmeter is low, it starts acting as a load and draws current from the source. A voltmeter is connected in parallel to the load, and the current drawn by the actual load also has some changes.

Whereas, a voltmeter with very high resistance, draws a very low value of current from the source and the load current is the same similar to without the voltmeter. Hence, the voltage across the load is approximately the same and we get the correct voltage reading.

Ques. what are the external resistance and internal resistance? (2 Marks)

Ans. Internal resistance is resistance within a battery, or another voltage source, which causes a drop in the source voltage when there is a current. And external resistance is generally referred to as the opposition to the flow currently offered by any load.

Ques. What is a function of resistance? (1.5 Marks)

Ans. The functions of resistance is:

The resistance limits the current, or in many cases, regulates the current if the source of voltage provides a constant voltage.
Resistance can consume power and then converts it into heat.

Ques. Why is resistance so important? (2 Marks)

Ans. The resistance of a conductor is important, as it controls the flow of current in the circuit.

Eg. according to ohm’s law; zero resistance of a circuit will have an infinite current value.

I = V/R

On putting 0 in R

1=V/0

Hence, it is a dangerously high current.

Ques. State a relation between current and resistance. (1.5 Marks)

Ans. The relation is inversely proportional.

The increases in resistance cause a decrease in current and the decrease in current causes increases in current.
When resistance is doubled, the current is halved and if resistance is increased 5 times, the current is decreased 5 times. So now when resistance is halved, the current doubles.

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CBSE CLASS XII Related Questions

1.
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.

2.
A charged particle $+q$ in an electric field $\vec{E}$ experiences a force in the direction of the electric field. As a result, its kinetic energy changes. Similarly, the charged particle also experiences a force when it moves in a magnetic field $\vec{B}$. But this magnetic force is perpendicular to both velocity $\vec{v}$ of the charged particle and the magnetic field $\vec{B}$, so it cannot change the kinetic energy of the charged particle. Consider two charged particles 1 and 2 of masses $m$ and $\frac{m}{2}$ having charges $-q$ and $+2q$ respectively. They are accelerated from rest through the same potential difference $V$ and acquire kinetic energy $K_1$ and $K_2$. Then they enter in a region of uniform magnetic field $\vec{B}$ perpendicular to their velocities.

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.
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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5.
An astronomical telescope consists of two converging lenses. One of them of large aperture and large focal length is called objective lens and the other one, of smaller focal length and smaller aperture is called the eyepiece. It is used to see distant objects which are not seen clearly with naked eyes. The image formed by the objective lens acts as an object for the eyepiece and the final image produced by the eyepiece is magnified.

6.
Write two advantages of reflecting telescope over refracting telescope.

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Unit of Resistance Important Questions

Important Questions On Unit Of Resistance

CBSE CLASS XII Related Questions

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.
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 ?

6.
Write two advantages of reflecting telescope over refracting telescope.

Similar Physics Concepts

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Unit of Resistance Important Questions

Important Questions On Unit Of Resistance

CBSE CLASS XII Related Questions

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.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 ?

6.Write two advantages of reflecting telescope over refracting telescope.

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

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.
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 ?

6.
Write two advantages of reflecting telescope over refracting telescope.