Punjab Physics 2023 Paper 2 — Solved MCQs

Question 1

If a positive charged particle of mass "m"is projected parallel to uniform electric field E. The acceleration of the particle is:

Accepted Answer

B. Option B — The correct answer is B. qE/m. When a positively charged particle is projected parallel to a uniform electric field E, it experiences a force F = qE, where q is the charge of the particle. According to Newton's second law, F = ma, where m is the mass of the particle and a is its acceleration. Therefore, the acceleration of the particle is given by:a = F/m = (qE)/m = qE/m.So, option B, qE/m, is the correct answer.

Question 2

If no fourth band is present on a carbon resistor then its tolerance will taken:

Accepted Answer

A. ±20% — When there is no fourth band present, the tolerance for carbon resistors is typically assumed to be ±20%.

Question 3

To display the given voltage along Y—axis on C.R.O, connected to it:

Accepted Answer

B. Option B — The Y plates are used to deflect the electron beam vertically, controlling the position of the beam along the Y-axis. This is how the given voltage is displayed along the Y-axis.

Question 4

If we want to increase the measuring range of voltmeter, the series high resistance value should be:

Accepted Answer

A. Increased — Increasing the series high resistance value would actually decrease the measuring range of the voltmeter. This is because the voltmeter measures voltage by dividing the voltage across its terminals by the total resistance (internal resistance + series resistance). Increasing the series resistance would decrease the total resistance, resulting in a smaller voltage drop across the voltmeter and thus a smaller measuring range.

Question 5

The direction of induced current in a circuit is determined by:

Accepted Answer

D. Lenz's law — Lenz's law states that the direction of the induced current is such that it opposes the change in magnetic flux that produced it. In other words, the induced current creates a magnetic field that opposes the original change in magnetic flux. This law helps determine the direction of the induced current in a circuit.

Question 6

For alternating current in a circuit, the inductor behaves like:

Accepted Answer

B. Resistor — An inductor in an AC circuit behaves like a resistor because both components impede the flow of current. However, the mechanism is different; a resistor resists the flow of current due to its fixed resistance, while an inductor resists changes in current flow due to its inductance.

Question 7

Metal detectors consist of:

Accepted Answer

D. L-C circuit — An L-C (inductor-capacitor) circuit is commonly used in metal detectors because it can resonate at a specific frequency when the inductance of the coil changes due to the presence of a metal object. This change in resonance frequency is detected by the circuit, indicating the presence of metal.

Question 8

At high frequency, RLC series circuit shows the behaviour as:

Accepted Answer

A. R-L circuit — At high frequencies, the inductive reactance (XL) of the inductor in the RLC series circuit increases significantly. This increase in XL dominates the behavior of the circuit, making it behave more like an R-L circuit where the inductor's impedance is dominant, and the capacitor's impedance is negligible. As a result, at high frequencies, an RLC series circuit behaves more like an R-L circuit.

Question 9

High temperature super conductors have a critical temperature greater than:

Accepted Answer

B. 77K — High-temperature superconductors are materials that exhibit superconductivity at temperatures above the boiling point of liquid nitrogen, which is 77K. These materials are called "high-temperature" superconductors because their critical temperatures are higher than those of conventional superconductors.

Question 10

The SI unit of current gain are:

Accepted Answer

D. No unit — Current gain is a dimensionless quantity, representing a ratio of two currents. As such, it is expressed without any specific unit.

Question 11

Which photon of light has least energy?

Accepted Answer

A. Red — Red light has the longest wavelength among the options given. According to the relationship between energy and wavelength for photons of light (E = h * f, where E is energy, h is Planck's constant, and f is frequency), photons with longer wavelengths have lower energies. Therefore, red light, with its longer wavelength, has the least energy among the options given.

Question 12

The rest mass of photon is:

Accepted Answer

C. Zero — Photons are massless particles, meaning they have no rest mass. They only have energy and momentum.

Question 13

X-rays are:

Accepted Answer

D. High energy photons — X-rays are a form of electromagnetic radiation, just like visible light and radio waves, but with higher energy. They are produced by accelerating electrons and are composed of high-energy photons.

Question 14

Heat produced due to fission reaction taking place in the core of nuclear reactor is about:

Accepted Answer

A. 500°C — This option is correct if we interpret it as the approximate temperature increase caused by the heat produced due to fission reactions in the core of a nuclear reactor. The actual temperature increase can vary but is typically in this range.

Question 15

Subatomic particles are divided into:

Accepted Answer

D. Three groups — Subatomic particles are typically divided into 3 groups:1. **Leptons**: These are elementary particles that do not experience the strong nuclear force. Examples include electrons and neutrinos.2. **Quarks**: These are elementary particles that do experience the strong nuclear force and combine to form composite particles called hadrons, such as protons and neutrons.3. **Bosons**: These are force carrier particles that mediate interactions between particles. Examples include photons (which mediate electromagnetic interactions) and gluons (which mediate the strong nuclear force).Therefore, the correct answer is D. 3 groups.

Question 16

A 3KQ resistor is connected in series with a capacitor of capacitance 2mF. The time constant for capacitor is:

Accepted Answer

C. 6 sec — Explanation will be added soon

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