Units & Measurements · Physics · COMEDK

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MCQ (Single Correct Answer)

1
Two physical quantities having the same dimensional formula $\left[\mathrm{M}^1 \mathrm{~L}^{-1} \mathrm{~T}^{-2}\right]$ are
COMEDK 2025 Evening Shift
2
In the expression $\mathrm{P}=\mathrm{El}^2 \mathrm{~m}^{-5} \mathrm{G}^{-2}$ where $\mathrm{E}, 1, \mathrm{~m}$ and G represent Energy, Angular Momentum, Mass and Gravitational Constant, the dimensions of P are
COMEDK 2025 Afternoon Shift
3

The nuclear forces

a. are central forces, independent of the spin of the nucleons.

b. have a short-range dominant over a distance of about a few fermi

c. are stronger being hundred times stronger than that of electromagnetic forces.

d. are independent of the nuclear charge.

Which of the above is not true?

COMEDK 2025 Morning Shift
4
Two light rays A and B travel from a medium into air at angles of incidence 15 degrees and 42 degrees respectively. In the medium, light travels 3 cm in 0.2 ns . Will there be total internal reflection? If so, which ray?
COMEDK 2025 Morning Shift
5
An electric field $E=3 x^2 i N C^{-1}$ exists in a certain region of space. The potential difference between the origin and at $x=4 m, V_0-V_4$ is
COMEDK 2025 Morning Shift
6
A symmetric double convex lens is cut into two equal parts by a plane perpendicular to the principal axis. If the power of the original lens is 4D, the difference between the powers of the original lens and the cut lens is
COMEDK 2025 Morning Shift
7
Three identical conducting balls $\mathrm{A}, \mathrm{B}$ and C , each of mass m , are thrown upward at an angle $\Theta$ to the horizontal with an initial speed $v$ in a region of space that has a uniform electric field $E$ downward along with the gravitational field $g . A$ is positively charged, B is uncharged and C is negatively charged. Rank the ranges R of these three balls in increasing order.
COMEDK 2025 Morning Shift
8
A wooden block floats with $\frac{3}{5}$ of its volume submerged in a tank of water. If a denser liquid is poured into the tank, the wooden block floats with half its volume in the liquid and the remaining half in water. The relative density of the liquid is:
COMEDK 2025 Morning Shift
9
A particle starts from rest and moves along the x -axis with a velocity that varies as $\mathrm{v}=\sqrt{100+4 x} \mathrm{~ms}^{-1}$. The acceleration of the particle is:
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10
If E is the amplitude of the electric field of the waves starting from the slits in a double slit experiment and $\theta$ is the phase difference between the waves reaching a point on the screen, the ratio of the amplitude of the resultant electric field at that point on the screen to the amplitude at one of the slits is
COMEDK 2025 Morning Shift
11
Two simple harmonic motions are represented by equations $y_1=0.5 \sin \left[200 \pi \mathrm{t}+\frac{\pi}{3}\right]$ and $y_1=0.5 \cos \pi \mathrm{t}$. The phase difference of the velocity of particle 1 with respect to the velocity of particle 2 is :
COMEDK 2025 Morning Shift
12
A vertical spring of spring constant $24 \mathrm{Nm}^{-1}$ is fixed on a table. A ball of mass 0.5 kg at a height 2 m above the free upper end of the spring falls vertically on the spring so that the spring is compressed by a distance of 50 cm . The net work done in the process is:
COMEDK 2025 Morning Shift
13
A sonometer string vibrates with a frequency of 400 Hz . When the length of the string is halved and the tension is altered, it begins to vibrate with a frequency of 200 Hz . The ratio of the new tension to the original tension in the string is:
COMEDK 2025 Morning Shift
14
In an experiment to measure the density of the material of a sphere, an error of $2 \%$ occurred while measuring the radius of a sphere and an error of $3 \%$ occurred while measuring the mass of the sphere. What is the maximum percentage error in the measurement of density?
COMEDK 2025 Morning Shift
15
If the binding energy per nucleon in $3 \mathrm{Li}^7$ and ${ }_2 \mathrm{He}^4$ nuclei are respectively 5.60 MeV and 7.06 MeV , then energy of $p$ in the reaction $p+{ }_3 \mathrm{Li}^7 \rightarrow 2{ }_2 \mathrm{He}^4$ is
COMEDK 2025 Morning Shift
16
A long solenoid has 400 turns. When a current of 100 A is passed through it, the resulting magnetic flux linked with each turn of the solenoid is 4 mWb . The self-inductance of the solenoid is
COMEDK 2025 Morning Shift
17
Which of the following is not true for a perfect conductor?
COMEDK 2025 Morning Shift
18
Young's modulus of the material of wires X and Y are in the ratio 4:1 and the areas of cross sections of the wires X and Y are in the ratio $2: 1$. If the same amount of load is applied to both the wires, the ratio of elongation produced in the wires X and Y will be: (Assume length of the wires X and Y initially are the same)
COMEDK 2025 Morning Shift
19

The dimension $$[\mathrm{ML}^{-1} \mathrm{~T}^{-2}]$$ is the physical quantity of

COMEDK 2024 Evening Shift
20

If units of mass, length and gravitational constant are chosen to fundamental units, the dimensions of time would be

COMEDK 2024 Afternoon Shift
21

Which of the given dimensional formula represents heat capacity

COMEDK 2024 Morning Shift
22

Find the value of '$$n$$' in the given equation $$P=\rho^n v^2$$ where '$$P$$' is the pressure, '$$\rho$$' density and '$$v$$' velocity.

COMEDK 2024 Morning Shift
23

The time dependence of a physical quantity P is give by $$\mathrm{P=P}_0 \exp \left(-\alpha t^2\right)$$ where $$\alpha$$ is a constant and $$t$$ is time. The constant $$\alpha$$ will

COMEDK 2023 Evening Shift
24

A tentative explanation of observations without assuming that it is true is called

COMEDK 2023 Evening Shift
25

Which of the following statement is incorrect?

COMEDK 2021
26

Which of the following technique is not used for measuring small time intervals?

COMEDK 2021
27

The relative errors in the measurement of two lengths 1.02 cm $$\pm$$ 0.01 cm and 9.89 cm $$\pm$$ 0.01 cm is

COMEDK 2021
28

Suppose refractive index $$\alpha$$ is given as $$ \alpha = A + {B \over {{\lambda ^2}}}$$, where A and B are constants and $$\lambda$$ is wavelength, then dimensions of B are same as that of

COMEDK 2020
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