Kpk Physics 2018 — Solved MCQs

Question 1

The minimum charge exists on ant body can not be less than _.

Accepted Answer

B. 1.6 x 10 -19 C — The minimum charge that exists on an ant's body cannot be less than the charge of a single electron, which is approximately $ -1.6 \times 10^{-19} $ coulombs.

Question 2

A charge 1e accelerated through a potential difference of 1000 V acquires K.E _

Accepted Answer

A. 1000 ev — When a charge of 1e (where e is the elementary charge) is accelerated through a potential difference of 1000 V, it acquires kinetic energy. The kinetic energy (K.E) acquired by the charge can be calculated using the formula:K.E=e×V

Question 3

A wire of uniform cross-section area A and length L and resistance R is cut into two equal parts. The specific resistance of each part will be _

Accepted Answer

D. Remains the same — When a wire of uniform cross-sectional area A and length L with resistance R is cut into two equal parts, each part will have half the length and half the resistance.The specific resistance (or resistivity) of each part will remain the same because it depends on the material of the wire, not its dimensions. Therefore, the specific resistance of each part will be the same as the original wire.

Question 4

The reciprocal of resistivity of the conductor is _

Accepted Answer

C. Conductivity — The reciprocal of resistivity of the conductor is conductivity

Question 5

The crystal always tends to fracture along definite directions by mechanical stress, this phenomenon is called _

Accepted Answer

A. Cleavage — The phenomenon where crystals tend to fracture along definite directions when subjected to mechanical stress is called cleavage.

Question 6

Magnetic flux per unit area of _

Accepted Answer

D. Both A and B — Magnetic flux per unit area is a measure of the magnetic field passing through a surface, typically denoted as BBB or Φ\PhiΦ and measured in units of teslas or webers per square meter.

Question 7

According to Len's law for electromagnetic induction that the quantity, which conserved is _

Accepted Answer

A. Energy — According to Lenz's Law for electromagnetic induction, the quantity that is conserved is energy.

Question 8

A balanced wheat-stone bridge is used to determine _

Accepted Answer

C. Unknown resistance — A balanced Wheatstone bridge is used to determine unknown resistance or impedance in a circuit.

Question 9

By doubling the frequency of alternating current _

Accepted Answer

B. XL becomes double — By doubling the frequency of alternating current:1. The reactance of capacitors Xc becomes half.2. The reactance of inductors XL becomes double.

Question 10

The value of alternating voltage is V=10 Sin2πt. The effective value will be _.

Accepted Answer

B. 7.07 V — The effective (RMS) value of an alternating voltage $ V = 10 \sin(2\pi t) $ is $ \frac{V_{max}}{\sqrt{2}} $, where $ V_{max} $ is the maximum voltage amplitude. In this case, $ V_{max} = 10 $ volts. So, the effective value is $ \frac{10}{\sqrt{2}} $ volts.

Question 11

A small piece of an un-magnetized material gets repelled when it is brought near a powerful magnet. The material is _

Accepted Answer

B. Diamagnetic — The material is likely diamagnetic.Diamagnetic materials are those that create a weak, opposing magnetic field when exposed to an external magnetic field, causing them to be repelled by magnets.

Question 12

Which one is not ferromagnetic in nature?

Accepted Answer

C. Copper — Copper is not ferromagnetic in nature

Question 13

The wavelength of a photon having energy of 6.625 x 10 -19 J _

Accepted Answer

C. 8 x 10^-7 J — The wavelength of a photon having energy of 6.625 x 10^-19 J can be calculated using the equation λ=E/hc

Question 14

In pair production, electrons and positrons are created, the electron is similar particle as that of positron except _

Accepted Answer

B. Charge — In pair production, electrons and positrons are created, the electron is similar to the positron except for having opposite charge.

Question 15

Which of the given properties of an electron is used in electron microscopy?

Accepted Answer

B. Wave nature — The property of an electron used in electron microscopy is its wave nature.

Question 16

The Balmer series converges at the shortest wavelength equal to _

Accepted Answer

C. 4/RH — The wavelength of the shortest line in the Balmer series can be calculated using the Rydberg formula:1/𝜆=𝑅𝐻(1/22−1/𝑛2)Therefore, the wavelength of the shortest line in the Balmer series is given by:𝜆min=4/𝑅𝐻

Question 17

With the help of laser beam we can produce _

Accepted Answer

D. All of these — All above mentioned options use the technology of laser

Question 18

α – particles is + vely charged particle, similar to _

Accepted Answer

C. Helium nuclei — An alpha particle is a positively charged particle, consisting of two protons and two neutrons bound together. It is essentially the same as a helium-4 nucleus. So, you could say it's similar to a helium nucleus.

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