Question # 1

A 4 m long string fixed at its ends resonate in 4 segments. The wavelength of the waveis:

Choose an answer

4m

0.5m

2m

0.25 m

The ratio of angular speeds of minute hand and hour hand of a watch is:

Choose an answer

1: 12

6: 1

12: 1

1: 6

The fundamental frequency of a closed organ pope is 50 Hz. The frequency ofsecond over tone is

Choose an answer

100hz

150hz

60hz

250hz

If a molecule with momentum mv strikes a wall and rebound then the change in momentum will be:

Choose an answer

-2 mv

Zero

2 mv

mv

A man pushes a wall and fails to displace it. He does:

Choose an answer

Negative work

Positive but not maximum work

No work at all

Maximum work

A parallel plate air capacitor is charged and then isolated. When a dielectric material is inserted between the plates of the capacitor , then which of the following does not change:

Choose an answer

Electric field between the plates

Charge on the plates

Potential difference across the plate

Energy stored in the capacitor

A longitudinal sinusoidal wave has wavelength of 1cm and a period of 2sec. Its wavevelocity is:

Choose an answer

50 cm/ sec

0.5 cm/ sec

5 m/ s

0.005 m/ sec

A radioactive isotope 𝟐𝟑𝟖 𝑼 decays consecutively to 𝟐𝟑𝟒 𝑼 the particles emitted are:

Choose an answer

One 𝛼 and one 𝛽

Two 𝛼 and one 𝛽

e 𝛼 and two 𝛽

Two 𝛼 and two 𝛽

If a car moves with a uniform speed of 2 ms-1 in a circle of radius 0.4m. Its angular speed is

Choose an answer

4 rad. s^-1

1.6 rad. s^-1

5 rad. s^-1

2.8 ms^-1

In a full wave rectifier with input frequency 50Hz. The frequency of pulsating D)C) received as an output across the load is

Choose an answer

50 Hz

100 Hz

500 Hz

zero

The pressure exerted on the walls on the vessel by gas molecules is defined as:

Choose an answer

Force per unit volume

Energy per unit area

mass per unit volume

None of these

The energy of photon of energy 1 eV is:

Choose an answer

1240 nm

1040 nm

1000 nm

620 nm

The energy which an -e acquires when accelerated through a potential difference of 1 volt is called?

Choose an answer

1 Joule

1 Electron volt

1 Erg

1 Watt

Compton Effect makes the use of the law of conservation of:

Choose an answer

Energy

Momentum

Charge

Both (a) & (b)

One degree of thermodynamics scale of temperature is called:

Choose an answer

Celsius

Fahrenheit

Kelvin

Radian

The product of resistance and conductance of a resistors is equal to:

Choose an answer

1

Conductivity

Resistivity

Zero

In Compton effect, it was considered that X-rays consist of:

Choose an answer

Electrons

Positrons

Photons

All of these

electrons from the surface of a metal when:

Choose an answer

It is heated to a high temperature

Radiation of suitable wavelength falls on it

Electrons of suitable velocity strike it

It is placed in a strong electric field

The kinetic energy of a body rotating with an angular speed 𝑚 depends on.

Choose an answer

angular speed

distribution of mass

neither (A) nor (B)

both (A) and (B)

What will be the number of photons emitted per second by 25 W source of monochromatic light of wavelength 600 nm:

Choose an answer

7.5 × 1017

7.5 × 1019

5.5 × 1019

5.5 × 1017

On slightly disturbing a body which is an unstable equilibrium, its center of gravity

Choose an answer

rises

falls

remains constant

first rises then falls

In order to increase the K.E of ejected photo electrons, there should be an increase in:

Choose an answer

Intensity of radiation

NoneI

Frequency of radiation

Both (b) & (c)

In a photocell, cesium coated oxidized silver emits electrons for :

Choose an answer

Visible light

Infrared light

Ultraviolet light

All of these

Which row is correct for fission and for fusion?

Choose an answer

Produces larger nuclei

Produces smaller nuclei

Speedometer of an automobile measures

Choose an answer

Average velocity

Instantaneous velocity

Acceleration

Instantaneous speed

In an ideal gas, the molecules have:

Choose an answer

Kinetic energy only

Potential energy only

Both KE and PE

None of these

A motor boat is travelling with a speed of 3.0 m/sec. If the force on it due to water flow is 500 N, the power of the boat is

Choose an answer

150 KW

1.5 KW

heat energy

chemical energy

Monochromatic light of wavelength 300 nm is incident normally on a surface of area 4 cm2.

If the intensity of light is 150 mW/m2; the rate at which photon strike the surface:

Choose an answer

2.53 × 1019

7.5 × 1019

9.1 × 1013

2.53 × 1013

Threshold wavelength for metal having work function 𝝋 is 𝝀. What is the threshold wavelength for metal having work function 2 𝒊𝒔:

Choose an answer

/𝟐

2

4

𝝀/𝟒

When a person lifts a body from ground work done by lifting force is?

Choose an answer

Positive

Negative

Zero

Half of positive maximum

During a negative β-decay

Choose an answer

An atomic electron is ejected

A neutron in the nucleus decays emitting an electron

An electron which already present within the nucleus is ejected

A part of binding energy of nuclei is converted into electron

Which one is the correct express of de-Broglie equation for the length of atoms of mass m at temp? T(k=Boltzmann’s constant):

Choose an answer

In uniform circular motion, the factor that remains constant is:

Choose an answer

Linear velocity

Acceleration

Speed

All of these

Kinetic energy of a body moving with speed of 10 ms-1 is 30 J. If its speed becomes30 ms-1 then its K.E becomes

Choose an answer

10J

270 J

90J

180 J

A rigid uniform bar of length 2.4 m is pivoted horizontally at its mid-point, weights are hung from two points of the bar as shown in diagram. To maintain horizontal equilibrium, a couple is applied to the bar: What is the torque and the direction of couple?

Choose an answer

40 N m clockwise

40 N m anti-clockwise

80 N m clockwise

80 N m anti-clockwise

When a particle moves in a circle the angle between it linear velocity and the angular velocity is always

Choose an answer

0°

180°

90°

none of them

A soap bubble is give a negative charge, then its radius:

Choose an answer

Decrease

Remains same

Increases

Bubble will disappear

Newton’s third law concerns the forces of interaction between two bodies. Which of the following statement relating to the third law is not correct:

Choose an answer

The two forces must be the same type

The two forces must act on different bodies

The two forces are always opposite in direction

The two forces are equal and opposite so the bodies are in equilibrium

The geostationary satellite is:

Choose an answer

Stationary

Rotating very fastly

Rotating with the period of earth

Rotating very slowly

A man has weight 980 N in a stationary lift. What will be his weight if the lift starts moving up with anacceleration of 4.9 ms^-2

Choose an answer

980 N

1470 N

1980 N

1460 N

A rider uses Motorcycle safety helmet that extends the time of collision during accident hence decreasing the

Choose an answer

Change of collisio

Force acting

Velocity

Impulse