Electricity and Resistance Quiz

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Q1) What is the SI unit of electric intensity?

Coulomb
Ampere
Tesla
Volt (correct)

Q2) What is the expression for force in vector form according to Coulomb's law?

$F = k \frac{q_1 q_2}{r^2}$ (correct)
$F = k \frac{q_2}{r^2}$
$F = k \frac{q_1}{r^2}$
$F = k \frac{q_1 q_2}{r}$

Q3) What is the SI unit of specific resistance?

Ampere
Volt
Ohm
Ohm-meter (correct)

Q4) What are the limitations of Ohm's law?

It is only applicable to metallic conductors. (C) Signup and view all the answers

Q5) How does temperature affect resistance?

Resistance decreases with temperature. (A) Signup and view all the answers

Q15) Define electric intensity and state its SI unit and dimensions.

Electric intensity is the amount of electric field strength per unit charge experienced by a test charge. Its SI unit is volt per meter (V/m) and its dimensions are [M L T^{-3} I^{-1}]. Signup and view all the answers

Q16) State Coulomb's law and obtain the expression for force in vector form.

Coulomb's law states that the force between two point charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance between them. The force in vector form can be obtained using the equation $\mathbf{F} = \frac{1}{4\pi\varepsilon_0} \frac{q_1 q_2}{r^2} \mathbf{\hat{r}}$, where $\varepsilon_0$ is the permittivity of free space, $q_1$ and $q_2$ are the magnitudes of the charges, $r$ is the distance between them, and $\mathbf{\hat{r}}$ is the unit vector in the direction from $q_1$ to $q_2$. Signup and view all the answers

Q17) Define specific resistance and give its SI unit.

Specific resistance, also known as resistivity, is a measure of the resistance offered by a material to the flow of electric current. It is defined as the resistance of a conductor of unit length and unit cross-sectional area. Its SI unit is ohm-meter (Ω·m). Signup and view all the answers

Q18) State and explain the limitations of Ohm's law.

The limitations of Ohm's law are as follows: 1) It is not applicable to all materials, especially non-ohmic materials like diodes and transistors. 2) It assumes that the temperature remains constant, but the resistance of most conductors increases with temperature. 3) It assumes that the physical dimensions of the conductor remain constant, but the resistance of a wire increases with its length and decreases with its cross-sectional area. 4) It assumes that the voltage is directly proportional to the current, but in some cases, the relationship may be nonlinear. Signup and view all the answers

Q19) Explain the effect of temperature on resistance.

The effect of temperature on resistance depends on the material. In most conductors, an increase in temperature leads to an increase in resistance. This is because as the temperature increases, the atoms or ions in the conductor vibrate more vigorously, impeding the flow of electrons. In some materials, such as semiconductors, the resistance decreases with an increase in temperature due to the increased availability of charge carriers. Signup and view all the answers