PAF Physics Academic Test 1

Two charges are placed in air, then in a medium with $K=81$. The force becomes:

1 Mark(s)

Your Answer:

$81F$ $81F$
$F/81$ $F/81$
$F/9$ $F/9$
$9F$ $9F$

The radius of gyration ($k$) is related to Moment of Inertia ($I$) and mass ($M$) by:

1 Mark(s)

Your Answer:

$I = Mk$ $I = Mk$
$I = Mk^2$ $I = Mk^2$
$I = M/k$ $I = M/k$
$I = M^2 k$ $I = M^2 k$

According to Newton's Law of Cooling, the rate of cooling is proportional to:

1 Mark(s)

Your Answer:

Difference in temperature Difference in temperature
Absolute temperature Absolute temperature
Surface area only Surface area only
Mass of body Mass of body

Materials which break immediately after the elastic limit are called:

1 Mark(s)

Your Answer:

Ductile Ductile
Brittle Brittle
Plastic Plastic
Malleable Malleable

Given $\vec{A} = 2\hat{i} + 3\hat{j}$ and $\vec{B} = \hat{i} + \hat{j}$. The component of $\vec{A}$ along $\vec{B}$ is:

1 Mark(s)

Your Answer:

$5/\sqrt{2}$ $5/\sqrt{2}$
$5/2$ $5/2$
$\sqrt{5}$ $\sqrt{5}$
$6$ $6$

At what height becomes the value of $g$ half of that on the surface? ($R$ = Radius of Earth)

1 Mark(s)

Your Answer:

$0.414 R$ $0.414 R$
$R$ $R$
$0.5 R$ $0.5 R$
$2 R$ $2 R$

Work done by a centripetal force on a particle moving in a circle is:

1 Mark(s)

Your Answer:

Zero Zero
Positive Positive
Negative Negative
Infinite Infinite

Magnetic monopole:

1 Mark(s)

Your Answer:

Exists Exists
Does not exist Does not exist
Exists in vacuum Exists in vacuum
Is a proton Is a proton

Two blocks $m_1=5kg, m_2=10kg$ are connected by a light string passing over a frictionless pulley. If the system is released from rest, the tension in the string is:

1 Mark(s)

Your Answer:

$33.3 N$ $33.3 N$
$50 N$ $50 N$
$66.7 N$ $66.7 N$
$100 N$ $100 N$

EM waves transport:

1 Mark(s)

Your Answer:

Energy only Energy only
Momentum only Momentum only
Both Energy and Momentum Both Energy and Momentum
Matter Matter

Which of the following is an example of a conservation law holding good for all forces?

1 Mark(s)

Your Answer:

Conservation of Energy Conservation of Energy
Conservation of Parity Conservation of Parity
Conservation of Strangeness Conservation of Strangeness
Conservation of Isospin Conservation of Isospin

The coefficient of restitution ($e$) for a perfectly inelastic collision is:

1 Mark(s)

Your Answer:

0 0
1 1
0.5 0.5
Infinite Infinite

The average kinetic energy of a molecule of an ideal gas is directly proportional to:

1 Mark(s)

Your Answer:

Pressure Pressure
Volume Volume
Absolute Temperature Absolute Temperature
Mass Mass

Heat is conducted through a slab of thickness $x$, area $A$. The rate of heat flow is inversely proportional to:

1 Mark(s)

Your Answer:

Area $A$ Area $A$
Thickness $x$ Thickness $x$
Temp diff $\Delta T$ Temp diff $\Delta T$
Conductivity $K$ Conductivity $K$

Control rods (Cadmium/Boron) are used to:

1 Mark(s)

Your Answer:

Slow neutrons Slow neutrons
Absorb neutrons Absorb neutrons
Reflect neutrons Reflect neutrons
Cool reactor Cool reactor

Mass defect $\Delta m$ is converted into energy according to:

1 Mark(s)

Your Answer:

$E = \Delta m c^2$ $E = \Delta m c^2$
$E = \Delta m c$ $E = \Delta m c$
$E = 1/2 \Delta m v^2$ $E = 1/2 \Delta m v^2$
$E = \Delta m / c^2$ $E = \Delta m / c^2$

Hydraulic lift works on the principle of:

1 Mark(s)

Your Answer:

Archimedes' Principle Archimedes' Principle
Bernoulli's Principle Bernoulli's Principle
Pascal's Law Pascal's Law
Torricelli's Law Torricelli's Law

The SI unit of Magnetic Field is:

1 Mark(s)

Your Answer:

Weber Weber
Tesla Tesla
Gauss Gauss
Henry Henry

A swimmer can swim at $5 m/s$ in still water. River flows at $3 m/s$. The shortest time to cross the river of width $100m$ is:

1 Mark(s)

Your Answer:

$20 s$ $20 s$
$25 s$ $25 s$
$33.3 s$ $33.3 s$
$15 s$ $15 s$

Which phenomenon is responsible for the glittering of a diamond?

1 Mark(s)

Your Answer:

Interference Interference
Total Internal Reflection Total Internal Reflection
Diffraction Diffraction
Polarization Polarization

In the Geocentric model of the universe (Ptolemy), the motion of planets was explained using:

1 Mark(s)

Your Answer:

Ellipses Ellipses
Epicycles Epicycles
Straight lines Straight lines
Parabolas Parabolas

A chain of length $L$ and mass $M$ is placed on a smooth table with $1/3$ of its length hanging over the edge. The work done to pull the hanging part back is:

1 Mark(s)

Your Answer:

$MgL/3$ $MgL/3$
$MgL/9$ $MgL/9$
$MgL/18$ $MgL/18$
$MgL/6$ $MgL/6$

The change in potential energy when a body of mass $m$ is raised to a height $h=R$ from surface is:

1 Mark(s)

Your Answer:

$mgR$ $mgR$
$2mgR$ $2mgR$
$0.5 mgR$ $0.5 mgR$
$0.25 mgR$ $0.25 mgR$

Water flows through a horizontal pipe. At a point where velocity is $v$, pressure is $P$. At another point where velocity is $2v$, the pressure is ($P_0$ is static term? No, use Bernoulli).

1 Mark(s)

Your Answer:

$P - \frac{3}{2}\rho v^2$ $P - \frac{3}{2}\rho v^2$
$P - \frac{1}{2}\rho v^2$ $P - \frac{1}{2}\rho v^2$
$P - 2\rho v^2$ $P - 2\rho v^2$
$P$ $P$

The energy associated with each degree of freedom per molecule is:

1 Mark(s)

Your Answer:

$k_B T$ $k_B T$
$\frac{1}{2} k_B T$ $\frac{1}{2} k_B T$
$\frac{3}{2} k_B T$ $\frac{3}{2} k_B T$
$RT$ $RT$

The time period of a simple pendulum depends on:

1 Mark(s)

Your Answer:

Mass of bob Mass of bob
Length of string Length of string
Amplitude of oscillation Amplitude of oscillation
Size of bob Size of bob

The value of Stefan's constant ($\sigma$) is:

1 Mark(s)

Your Answer:

$5.67 \times 10^{-8} W/m^2 K^4$ $5.67 \times 10^{-8} W/m^2 K^4$
$6.67 \times 10^{-11} W/m^2 K^4$ $6.67 \times 10^{-11} W/m^2 K^4$
$3 \times 10^8 W/m^2 K^4$ $3 \times 10^8 W/m^2 K^4$
$1.38 \times 10^{-23} W/m^2 K^4$ $1.38 \times 10^{-23} W/m^2 K^4$

A particle is projected from the ground with velocity $u$ at angle $\theta$. Its average velocity between the point of projection and the highest point is:

1 Mark(s)

Your Answer:

$u \cos\theta$ $u \cos\theta$
$u/2$ $u/2$
$\frac{u}{2}\sqrt{1+3\cos^2\theta}$ $\frac{u}{2}\sqrt{1+3\cos^2\theta}$
$u$ $u$

Which of the following is a state function?

1 Mark(s)

Your Answer:

Internal Energy Internal Energy
Work Work
Heat Heat
Heat - Work Heat - Work

When a wave reflects from a rigid boundary, the phase change is:

1 Mark(s)

Your Answer:

$0$ $0$
$\pi/2$ $\pi/2$
$\pi$ $\pi$
$2\pi$ $2\pi$

The momentum of a photon is:

1 Mark(s)

Your Answer:

$E c$ $E c$
$h/\lambda$ $h/\lambda$
$h \lambda$ $h \lambda$
$c/h$ $c/h$

When $n$ identical cells ($E, r$) are in series, total emf is:

1 Mark(s)

Your Answer:

$nE$ $nE$
$E$ $E$
$E/n$ $E/n$
$n^2 E$ $n^2 E$

A particle starts from rest with acceleration $2 m/s^2$. The distance covered in the 3rd second is:

1 Mark(s)

Your Answer:

$9 m$ $9 m$
$5 m$ $5 m$
$4 m$ $4 m$
$6 m$ $6 m$

Lyman series lies in which region?

1 Mark(s)

Your Answer:

Visible Visible
Ultraviolet Ultraviolet
Infrared Infrared
X-ray X-ray

Formula for magnetic flux:

1 Mark(s)

Your Answer:

$BA \cos\theta$ $BA \cos\theta$
$BA \sin\theta$ $BA \sin\theta$
$B/A$ $B/A$
$B \times A$ $B \times A$

A wheel of moment of inertia $10 kg \cdot m^2$ is rotating at $10 rad/s$. The energy required to stop it is:

1 Mark(s)

Your Answer:

$1000 J$ $1000 J$
$500 J$ $500 J$
$250 J$ $250 J$
$100 J$ $100 J$

Photons are electrically:

1 Mark(s)

Your Answer:

Positive Positive
Negative Negative
Neutral Neutral
Charged Charged

Two masses $m_1$ and $m_2$ ($m_1 > m_2$) are connected by a string passing over a frictionless pulley. The acceleration of the system is:

1 Mark(s)

Your Answer:

$g$ $g$
$\frac{m_1 - m_2}{m_1 + m_2}g$ $\frac{m_1 - m_2}{m_1 + m_2}g$
$\frac{m_1 + m_2}{m_1 - m_2}g$ $\frac{m_1 + m_2}{m_1 - m_2}g$
$\frac{2m_1m_2}{m_1+m_2}g$ $\frac{2m_1m_2}{m_1+m_2}g$

A force $\vec{F} = 3\hat{i} + 4\hat{j}$ acts on a body and displaces it by $\vec{S} = 3\hat{i} + 4\hat{j}$. The work done is:

1 Mark(s)

Your Answer:

$7 J$ $7 J$
$25 J$ $25 J$
$12 J$ $12 J$
$50 J$ $50 J$

The phase difference $\phi$ corresponding to a path difference $\lambda$ is:

1 Mark(s)

Your Answer:

$\pi$ $\pi$
$\pi/2$ $\pi/2$
$2\pi$ $2\pi$
$4\pi$ $4\pi$

The frequency range of FM radio is approx:

1 Mark(s)

Your Answer:

500-1500 kHz 500-1500 kHz
88-108 MHz 88-108 MHz
1-10 GHz 1-10 GHz
30-300 Hz 30-300 Hz

The number of oscillations per unit time is called:

1 Mark(s)

Your Answer:

Time Period Time Period
Frequency Frequency
Amplitude Amplitude
Phase Phase

Two vectors $\vec{A}$ and $\vec{B}$ have magnitudes 3 and 5. Their dot product is 7.5. The angle between them is:

1 Mark(s)

Your Answer:

$30^\circ$ $30^\circ$
$60^\circ$ $60^\circ$
$90^\circ$ $90^\circ$
$120^\circ$ $120^\circ$

A point moves such that its displacement is $x = t^3 - 3t^2 + 5$. The distance traveled in the first 3 seconds is:

1 Mark(s)

Your Answer:

$0 m$ $0 m$
$8 m$ $8 m$
$5 m$ $5 m$
$4 m$ $4 m$

The time taken to complete one vibration is called:

1 Mark(s)

Your Answer:

Frequency Frequency
Amplitude Amplitude
Time Period Time Period
Phase Phase

Motional emf induced in a rod of length $l$ moving with $v$ in $B$:

1 Mark(s)

Your Answer:

$Bvl$ $Bvl$
$Bv/l$ $Bv/l$
$Bl/v$ $Bl/v$
$1/2 Bvl$ $1/2 Bvl$

Two blocks of mass 4kg and 2kg are placed side by side on a smooth surface. A force of 12N acts on the 4kg block. The contact force between them is:

1 Mark(s)

Your Answer:

$4 N$ $4 N$
$8 N$ $8 N$
$12 N$ $12 N$
$6 N$ $6 N$

A manometer connected to a gas container shows a height difference of 10 cm of Hg. The gauge pressure is:

1 Mark(s)

Your Answer:

10 Pa 10 Pa
10 cm Hg 10 cm Hg
76 cm Hg 76 cm Hg
86 cm Hg 86 cm Hg

Second Law of Thermodynamics implies that heat cannot flow spontaneously from:

1 Mark(s)

Your Answer:

Hot to Cold Hot to Cold
Cold to Hot Cold to Hot
High pressure to Low pressure High pressure to Low pressure
Vacuum to Air Vacuum to Air

Energy stored in an inductor:

1 Mark(s)

Your Answer:

$LI^2$ $LI^2$
$1/2 L I^2$ $1/2 L I^2$
$1/2 L^2 I$ $1/2 L^2 I$
$1/2 L I$ $1/2 L I$

In uniform circular motion, the angle between the velocity vector and acceleration vector is:

1 Mark(s)

Your Answer:

$0^\circ$ $0^\circ$
$90^\circ$ $90^\circ$
$180^\circ$ $180^\circ$
$45^\circ$ $45^\circ$

Who experimentally proved the existence of EM waves?

1 Mark(s)

Your Answer:

Maxwell Maxwell
Hertz Hertz
Marconi Marconi
Bose Bose

Angular momentum is conserved if:

1 Mark(s)

Your Answer:

Force is zero Force is zero
Energy is zero Energy is zero
Momentum is zero Momentum is zero
Torque is zero Torque is zero

The radius of curvature of the reflecting surface of a spherical mirror is $R$. Its focal length $f$ is:

1 Mark(s)

Your Answer:

$R/2$ $R/2$
$2R$ $2R$
$R$ $R$
$R/3$ $R/3$

Power consumed in a pure capacitor is:

1 Mark(s)

Your Answer:

Zero Zero
$1/2 CV^2$ $1/2 CV^2$
$VI$ $VI$
$I^2 X_C$ $I^2 X_C$

Planets revolve around the Sun in:

1 Mark(s)

Your Answer:

Circular orbits Circular orbits
Elliptical orbits Elliptical orbits
Parabolic paths Parabolic paths
Hyperbolic paths Hyperbolic paths

The total energy of a particle executing SHM is proportional to:

1 Mark(s)

Your Answer:

Amplitude Amplitude
Square of Amplitude Square of Amplitude
Frequency Frequency
Mass Mass

Two waves of intensities $I$ and $4I$ superimpose. The minimum intensity is:

1 Mark(s)

Your Answer:

$I$ $I$
$3I$ $3I$
$5I$ $5I$
Zero Zero

The pressure exerted by an ideal gas is given by:

1 Mark(s)

Your Answer:

$\rho v^2$ $\rho v^2$
$\frac{1}{2} \rho v^2$ $\frac{1}{2} \rho v^2$
$\frac{1}{3} \rho \bar{v}^2$ $\frac{1}{3} \rho \bar{v}^2$
$\frac{2}{3} \rho \bar{v}^2$ $\frac{2}{3} \rho \bar{v}^2$

The unit of Torque is:

1 Mark(s)

Your Answer:

$N \cdot m$ $N \cdot m$
$N/m$ $N/m$
$J/s$ $J/s$
$kg \cdot m/s$ $kg \cdot m/s$

Power factor of an LCR circuit is:

1 Mark(s)

Your Answer:

$Z/R$ $Z/R$
$R/X$ $R/X$
$R/Z$ $R/Z$
$X/Z$ $X/Z$

A car of mass $m$ starts from rest and accelerates so that instantaneous power $P$ is constant. The velocity at time $t$ is proportional to:

1 Mark(s)

Your Answer:

$t$ $t$
$t^{1/2}$ $t^{1/2}$
$t^2$ $t^2$
$t^{-1/2}$ $t^{-1/2}$

Stopping potential depends on:

1 Mark(s)

Your Answer:

Intensity Intensity
Frequency Frequency
Distance Distance
Time Time

A lens that is thicker at the middle than at the edges is called:

1 Mark(s)

Your Answer:

Convex lens Convex lens
Concave lens Concave lens
Plane lens Plane lens
Cylindrical lens Cylindrical lens

In an isochoric process, heat supplied is used to:

1 Mark(s)

Your Answer:

Increase Internal Energy Increase Internal Energy
Do external work Do external work
Decrease pressure Decrease pressure
Option 4 Option 4

1 Horse Power (hp) is equal to:

1 Mark(s)

Your Answer:

700 Watts 700 Watts
746 Watts 746 Watts
1000 Watts 1000 Watts
500 Watts 500 Watts

Van de Graaff generator is used to generate:

1 Mark(s)

Your Answer:

High Voltage High Voltage
High Current High Current
High Resistance High Resistance
Magnetic Field Magnetic Field

Capacitive Reactance $X_C$ is:

1 Mark(s)

Your Answer:

$\omega C$ $\omega C$
$1/\omega C$ $1/\omega C$
$\omega / C$ $\omega / C$
$C / \omega$ $C / \omega$

Which series lies in the Infrared region?

1 Mark(s)

Your Answer:

Lyman Lyman
Balmer Balmer
Paschen Paschen
None None

The angle of contact for pure water and clean glass is approximately:

1 Mark(s)

Your Answer:

$0^\circ$ $0^\circ$
$90^\circ$ $90^\circ$
$135^\circ$ $135^\circ$
$180^\circ$ $180^\circ$

Materials attracted strongly by magnets are:

1 Mark(s)

Your Answer:

Diamagnetic Diamagnetic
Paramagnetic Paramagnetic
Ferromagnetic Ferromagnetic
Non-magnetic Non-magnetic

Electromagnetic waves are produced by:

1 Mark(s)

Your Answer:

Static charges Static charges
Moving charges (const v) Moving charges (const v)
Accelerated charges Accelerated charges
Magnets Magnets

The internal energy of an ideal gas depends only on:

1 Mark(s)

Your Answer:

Pressure Pressure
Volume Volume
Temperature Temperature
Size of molecule Size of molecule

When sound travels from air to water, which quantity remains unchanged?

1 Mark(s)

Your Answer:

Frequency Frequency
Wavelength Wavelength
Speed Speed
Amplitude Amplitude

A solid cylinder of mass $20 kg$ rotates about its axis with angular speed $100 rad/s$. The radius is $0.25 m$. The kinetic energy of rotation is:

1 Mark(s)

Your Answer:

$3125 J$ $3125 J$
$6250 J$ $6250 J$
$1250 J$ $1250 J$
$2500 J$ $2500 J$

Evaluating Your Answers

PAF Physics Academic Test 1 : Question 1 of 75