Punjab Physics 2017 Paper 2 — Solved MCQs

Question 1

If the distance between two point charges is halved, the electric intensity becomes:

Accepted Answer

D. 4 times — When the distance between two point charges is halved, the electric intensity between them becomes four times. This is because the electric field strength is inversely proportional to the square of the distance between the charges (E ∝ 1/r²).

Question 2

The drum in photo copier is coated with layer of:

Accepted Answer

C. Selenium — Selenium is commonly used as the coating on the drum in a photocopier. Selenium is a photoconductive material, meaning its electrical conductivity increases when exposed to light. This property allows the drum to hold an electrostatic charge and attract toner particles, which are then transferred to paper to create the image.

Question 3

A rheostat can operate as:

Accepted Answer

B. Potential divider — A rheostat can operate as a potential divider. By adjusting the position of the sliding contact along its resistance, a rheostat can divide the voltage across it into two parts, creating a variable voltage output.

Question 4

Force on a moving charge in a magnetic field is given by:

Accepted Answer

D. D — Explanation will be added soon

Question 5

Current passing through the coil of galvanometer is:

Accepted Answer

D. D — Explanation will be added soon

Question 6

One Henry is:

Accepted Answer

A. Vsa-1 — One henry (H) is equivalent to one volt-second per ampere (V·s/A). This is the unit of inductance, representing the amount of inductance in a circuit where an electromotive force of one volt is produced when the current is changing at a rate of one ampere per second.

Question 7

If the coil is wound on an iron core, the magnetic flux through it will:

Accepted Answer

B. Increases — When a coil is wound on an iron core and a current is passed through the coil, the magnetic field generated by the current induces magnetization in the iron core. This increases the magnetic flux through the coil compared to when there is no core present.

Question 8

One of the source of an A.C voltage is:

Accepted Answer

A. Motor — A motor can be used as a source of AC voltage if it is operated as a generator. When a motor is rotated manually or by an external force, it can generate an alternating current (AC) voltage. This is known as a "dynamo" effect, where mechanical energy is converted into electrical energy.

Question 9

If Io is the peak value of A.C current, then the root mean square(rms) value of current will be:

Accepted Answer

D. D — Explanation will be added soon

Question 10

The crystalline structure of NaCl is:

Accepted Answer

A. Cubical — The crystalline structure of sodium chloride (NaCl) is cubic. It forms a crystal lattice in which each sodium ion is surrounded by six chloride ions, and each chloride ion is surrounded by six sodium ions, arranged in a cubic pattern.

Question 11

A diode charactersitics curve is a plot between:

Accepted Answer

C. Voltage and current — A diode characteristics curve is a plot of voltage (on the x-axis) and current (on the y-axis). It shows how the current through a diode varies with the voltage applied across it, indicating the diode's behavior under different voltage conditions.

Question 12

Voltage gain of the common emitter npn-transister as an amplifier is:

Accepted Answer

D. D — Explanation will be added soon

Question 13

0.1 kg mass will be equivalent to the energy:

Accepted Answer

B. 6x1019 Joules — This is the correct answer. The energy equivalent of mass can be calculated using Einstein's famous equation, E = mc2, where E is the energy, m is the mass, and c is the speed of light in a vacuum (approximately 3x108 m/s). For 0.1 kg of mass, the energy equivalent is:E = (0.1 kg) * (3x108 m/s)2 = 0.1 * 9x1016 = 6x1015 Joules

Question 14

The maximum kinetic energy of emitted photoelectrons depends upon:

Accepted Answer

B. Frequency of the incident light — The maximum kinetic energy of emitted photoelectrons depends on the frequency of the incident light. According to the photoelectric effect equation, the energy of a photon (E) is given by E = hf, where h is the Planck constant and f is the frequency of the light. The maximum kinetic energy of an emitted photoelectron is given by K.E. = hf - φ, where φ is the work function of the metal. Thus, the frequency of the incident light directly determines the maximum kinetic energy of the emitted photoelectrons.

Question 15

Balmer empirical formula explains the electromagnetic radiation of any excited atom in terms of their:

Accepted Answer

C. Wavelength — Balmer's formula is an empirical equation that describes the wavelengths of the visible spectral lines emitted by hydrogen atoms. It is based on observations and provides a simple formula to calculate the wavelengths of these lines based on the integer values of the spectral series.

Question 16

Gm-counter uses:

Accepted Answer

D. Neon and bromine — GM counters commonly use a gas mixture that includes neon as the ionization gas and a small amount of bromine as the quenching gas. The bromine helps to quickly stop the discharge of the detector after each ionization event, allowing the counter to detect subsequent events.

Question 17

How many times, the α — Particle is more massive than electron?

Accepted Answer

B. 7332 — Option A is the correct answer. The mass of an alpha (α) particle is approximately 4 atomic mass units (amu), while the mass of an electron is approximately 1/1836 amu. Therefore, the ratio of the mass of an alpha particle to that of an electron is:[ frac{{text{{Mass of α-particle}}}}{{text{{Mass of electron}}}} = frac{4 text{{ amu}}}{{1/1836 	ext{{ amu}}}} \approx 4 	imes 1836 \approx 7332 ]So, an alpha particle is approximately 7332 times more massive than an electron.

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