Physics MCQ Quiz - Objective Question with Answer for Physics - Download Free PDF

The correct answer is Altimeter.

• The altimeter is used to measure the height of an aircraft above a fixed level.

Key Points

• Altimeter:
  • An altimeter is a device that measures altitude at a location's distance above sea level.

Additional Information

• A barometer is used to measure atmospheric pressure.
• A fathometer is used to measure the depth of water.
• A wattmeter is an instrument for measuring the electric active power. 

The correct answer is a fathometer.

Key Points

• A fathometer is a device that is used to measure the depth of water in the ocean using the principle of reflection of sound or echo sounding.
• The device transmits sound waves through the water which on striking the bottom, return as the echo.
• This echo is received and analyzed by the hydrophone echo receiver to give the depth of water.
• The fathometer was patented on 22 July 1913 by Alexander Behm.

Additional Information

• A barometer is a scientific instrument used to measure atmospheric pressure, also called barometric pressure.
• Lactometer is an instrument used in measuring the volume of cream in a sample of milk, and the probable amount of water, if any, which has been added to it.
• A dynamometer is a device used for measuring the torque and brake power required to operate a driven machine. It has a device to measure the frictional resistance.

The correct answer is  Voltmeter.

Key Points

• A voltmeter is an instrument used to measure the potential difference.
• A voltmeter is used between two points in an electric circuit to measure the potential difference between those two points.
• Voltmeter was invented in 1819 by Hans Oersted.
• The symbol for the voltmeter is shown below:
• 

Additional Information

• The ammeter is the instrument used for measuring current in the electrical circuit.
• The galvanometer is the instrument that detects current in the electrical circuit.

The correct answer is Barometer.

Key Points

• The Barometer was invented by Italian Physicist Evangelista Toricelli in 1643.
• The Barometer measures atmospheric pressure in units of measurement called atmospheres or bars.
• There are two main types of Barometer:
  • Mercury Barometer
  • Aneroid Barometer.
• When there is a sudden fall in the barometer, it is an indication of a storm because the atmospheric pressure decreases all of a sudden during the storm.
• The Barometric Pressure is an indicator of the weight of the column of air ranges from a historic high of 32.01 inches to an all-time low of 25.9 inches.

Additional Information

Image of Barometer:

The correct answer is Altitude.

• Altitude:
  • An altimeter is an instrument used to measure altitudes in aircraft.
  • The measurement of altitude using altimeter is called altimetry.

Additional Information 

CONCEPT:

• Wave: The disturbance that transfers energy from one place to another is called a wave.

There are mainly two types of waves:

1. Transverse waves: The wave in which the movement of the particles is at right angles to the motion of the energy is called a transverse wave. Light is an example of a transverse wave.
2. Longitudinal wave: The wave in which the movement of the particles is parallel to the motion of the energy is called a longitudinal wave. The sound wave is an example of a longitudinal wave.

EXPLANATION:

• Light-wave is a transverse wave because its components vibrate perpendicular to its direction of propagation. So option 1 is correct.

The correct answer is Newton's first law.

Key Points

• Newton's laws of motion-
  • ​Newton’s first law states that, if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed unless it is acted upon by force.
    • This postulate is known as the law of inertia. The law of inertia was first formulated by Galileo Galilei for horizontal motion on Earth and was later generalized by René Descartes.
    • Before Galileo, it had been thought that all horizontal motion required a direct cause. Still, Galileo deduced from his experiments that a body in motion would remain in motion unless a force (such as friction) caused it to come to rest.
  • Newton’s second law is a quantitative description of the changes that a force can produce in a body's motion.
    • It states that the time rate of change of a body's momentum is equal in both magnitude and direction to the force imposed on it.
    • The momentum of a body is equal to the product of its mass and its velocity. Momentum, like velocity, is a vector quantity, having both magnitude and direction.
    • A force applied to a body can change the magnitude of the momentum, direction, or both.
    • For a body whose mass m is constant, it can be written in F = ma, where F (force) and an (acceleration) are vector quantities.
    • If a body has a net force acting on it, it is accelerated by the equation. Conversely, if a body is not accelerated, there is no net force acting on it.
  • Newton’s third law states that when two bodies interact, they apply forces to one another that are equal in magnitude and opposite in direction.
  • The third law is also known as the law of action and reaction. This law is important in analyzing static equilibrium problems, where all forces are balanced, but it also applies to bodies in uniform or accelerated motion.
  • The forces it describes are real ones, not mere bookkeeping devices. For example, a book resting on a table applies a downward force equal to its weight on the table.
  • According to the third law, the table applies an equal and opposite force to the book. This force occurs because the book's weight causes the table to deform slightly so that it pushes back on the book like a coiled spring.

The correct answer is At the centre of the Earth.

• The centre of the Earth is such that if we are at that place, the mass around us can be considered to be condensed at the surface of the Earth itself, i.e considering the Earth as a spherical shell.
• Inside a spherical shell, there is no change in potential as one moves inside, and since only a change in potential implies a force there is no force.
• Hence the acceleration due to gravity is zero at the centre of the Earth.

The correct answer is Gamma Rays.

Key Points

• Gamma rays have the shortest wavelength and highest frequency (energy) in the electromagnetic spectrum.
• They are electromagnetic waves with wavelengths in the range of 10^-12m and frequencies around 10²⁰- 10²⁴ Hz.
• They have a high penetrating power.
• They are a result of decaying radioactive material and can also be found in outer space.
• They are used in medical applications for sterilisation of equipment and cancer treatment.

Additional Information

•  Other radiations in the Electromagnetic spectrum are:

The correct answer is 342 m.

CONCEPT:

• Echo: If we shout or clap near a suitable reflecting object such as a tall building or a mountain, we will hear the same sound again a little later. This sound which we hear is called an echo.
  • Echoes are heard due to the phenomenon of Reflection of sound waves.
  • To hear the echo clearly, the reflecting object must be more than 17.2 m from the sound source for the echo to be heard by a person standing at the source.

CALCULATION:

Speed of sound = 342 m/s.

The time is taken for hearing an echo = 2s.​

• The speed of sound is

\(⇒ Speed (v)= \frac{distance (d)}{time (t)}\)

Distance travelled = 2d = v × t

⇒ 2 × d = 342 × 2

⇒ d = (342 × 2)/2

The correct answer is the Microwave.

Key Points

• A microwave oven uses microwaves to heat food.
• In the case of microwave ovens, the commonly used radio wave frequency is roughly 2,500 megahertz (2.5 gigahertz).
• Radio waves in this frequency range absorbed by water, fats, and sugars. When they are absorbed they are converted directly into atomic motion or vibration.
• Therefore heavy motion or vibration is converted into heat.

Important Points

• Microwaves are not absorbed by most plastics, glass, or ceramics.
• The frequency of the Microwave equals the resonance frequency of water. Therefore foods could be heated up by the oscillation of water molecules.

Additional Information

• An Electric heater, Electric blub (with filament), Electric iron is the electrical device that converts an electric current into heat.
• They working on the principle of the Joule heating effect.
  • An electric current passing through a resistor will convert that electrical energy into heat energy.

The correct answer is 12250 W.

Concept:

• Power: Power is the amount of energy transferred or converted per unit time.
  • The unit of power is watt or J/s.
  • Its dimensional formula is: [M L² T^-3].

Calculation:

Given: v = 700 m/s, m = 50 g = 0.05 kg, n/t = 60 bullets/min ⇒  1 bullet/s

The power developed by the gun is given by formula -

Power = Work done / time = Energy consumed / time

\(Power = n \times \frac{{\frac{1}{2}m{v^2}}}{t}\)

\(Power = \frac{n}{t}\; \times \frac{1}{2}m{v^2}\)

\(Power = 1 \times \frac{1}{2} \times 0.05 \times {700^2}\)

Power = 12250 watt

Calculations:

Given,

Distance of the object from the lens = u = -10 cm

Refractive index of the lens = µ = 1.5

The Radii of curvature of the lens are 20 cm in magnitude

R₁ = 20 cm and R₂ = -20 cm          (As per sign convention)

According to Len's Maker's formula

\(\frac{1}{f}=(\mu - 1)(\frac{1}{R_1}-\frac{1}{R_2})=(1.5-1)(\frac{1}{20}-\frac{1}{-20})\\ =0.5 \times \frac{2}{20}=\frac{1}{20}\\ or, \; f=20 \; cm \)

From the Lens equation,

\(\frac{1}{v}-\frac{1}{u}=\frac{1}{f}\\ \frac{1}{v}=\frac{1}{f}+\frac{1}{u}\\ or, \; v=\frac{fu}{u+f}=\frac{20 \times (-10)}{-10+20}=\frac{-200}{10}=-20 \; cm\)

The image is formed 20 cm on the same side as the object.

The correct answer is 10-4 microns.

Key Points

Read the question ,it is asking value  in microns not meter.

If asked in meters then the value will be 1 Angstroms  = 10^-10 m.

But asked in microns

• 1 mm = 10^-3 m
• 1 micron = 10^-3 mm
  • ⇒ 1 micron = 10-6 m
• 1 Angstrom = 10^-10 m
  • 1 Angstrom = 10-10 m = 10-10 × 106 micron = 10-4 micron.

Confusion Points

1 Angstrom = 10^-10 meter

1 Angstrom =  10^-4 micron

Additional Information

• An Angstrom is a unit of length used to measure very small distances.
• 1 Angstroms to = 0.0001 Microns 
• It is named after Anders Jonas Ångström (Swedish physicist).
• A micron is one-millionth of a meter (10−6 m) and one Angstrom is 10-4 micron.

The correct answer is Ohm.

Key Points

• Impedance is the total sum of resistance and reactance.
• The SI Unit of Impedance(Z), resistance(R), and reactance(X) is Ohm(Ω).
• Reactance is a kind of imaginary resistance offered by electrical components like Capacitance and Inductor.
  • Reactance offered by the Inductor is called Inductive reactance, given as X_L = 2πfL.
  • Reactance offered by the Capacitor is called Capacitor reactance, given as  \(X_{C}=\frac{1}{2\pi fC}\).
  • Where 'f' - frequency of the source, 'L' - Inductance, and 'C' - Capacitance.

Additional Information