Test on Ohm’s law

Question 1: Materials that offer very high resistance to current flow are known as conductors.

A. Yes

B. No

Explanation: Resistance is the opposition to the flow of electric current. Materials that offer very little resistance are called conductors, while those that offer very high resistance are called insulators.

Question 2: Based on the provided study materials, which statement accurately distinguishes between ohmic and non-ohmic devices?

A. Ohmic devices are specifically designed to obey a linear relationship between voltage and current, while non-ohmic devices do not exhibit this linear relationship.

B. Non-ohmic devices strictly follow Ohm's Law, whereas ohmic devices have resistance that changes with voltage or current.

C. The V-A characteristic of an ohmic device is a curve, while for a non-ohmic device it is a straight line through the origin.

D. Ohmic devices are excellent conductors with zero resistance, unlike non-ohmic devices which are insulators.

Explanation: The study materials state that 'Ohm's Law is applicable to many materials and components, especially resistors, which are specifically designed to obey this linear relationship over a wide range of voltages and currents. Such components are called 'ohmic' devices.' It further clarifies, 'Components that do not exhibit this linear relationship, such as diodes or transistors, are called 'non-ohmic' devices, and their resistance changes with voltage or current.' Option 0 directly reflects this distinction. Option 1 is incorrect because it reverses the definitions. Option 2 is incorrect as the V-A characteristic of an ideal ohmic resistor is a straight line, and non-ohmic devices do not exhibit a linear relationship. Option 3 is incorrect because the materials do not describe ohmic devices as having zero resistance or non-ohmic devices as insulators.

Question 3: The resistivity of a material changes with the length of the conductor.

A. Yes

B. No

Explanation: Resistivity (ρ) is described as an intrinsic property of the material itself. While the length (l) of a conductor affects its overall resistance (R = ρ · l / S), it does not change the material's resistivity.

Question 4: Electrical power is the rate at which electrical energy is converted into other forms of energy or transferred within a circuit.

A. Yes

B. No

Explanation: The study materials define electrical power (P) as the rate at which electrical energy is converted into other forms of energy (like heat, light, or mechanical energy) or transferred within a circuit.

Question 5: A current of 0.5 A flows through a resistor with a resistance of 60 Ω. What is the voltage across the resistor?

A. 120 V

B. 30 V

C. 0.0083 V

D. 60.5 V

Explanation: To calculate the voltage (U) across the resistor, we use Ohm's Law: U = I · R. Given the current (I) is 0.5 A and the resistance (R) is 60 Ω, the calculation is U = 0.5 A · 60 Ω = 30 V.