Physics MCQs

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Physics MCQs

Practice the latest Physics MCQs with answers and detailed explanations. This section includes chapter-wise multiple-choice questions covering mechanics, motion, force, work and energy, heat, light, electricity, magnetism, modern physics, waves, optics, and other important topics. These exam-oriented MCQs are ideal for Class 9–12, NEET, JEE, CUET, SSC, Banking, Railway, JKSSB, Defence, Police, and other competitive exams.

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Question #41
Which of the following materials would have the highest electrical resistance, assuming equal length and cross-sectional area?
A. Silver
B. Copper
C. Aluminum
D. Nichrome
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Correct Answer: Option D

Explanation:
Resistance depends on the resistivity of the material (R = ρL/A). Silver and copper are excellent conductors with very low resistivity. Aluminum is also a good conductor. Nichrome is an alloy (nickel, chromium, and often iron) with a resistivity about 60 times higher than that of copper, making it a resistor used in heating elements.
This question belongs to: Science Physics
Question #42
If three resistors of 2 Ω, 3 Ω, and 6 Ω are connected in parallel, the equivalent resistance of the combination is:
A. 11 Ω
B. 2 Ω
C. 1 Ω
D. 0.5 Ω
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Correct Answer: Option C

Explanation:
For resistors in parallel, the reciprocal of the equivalent resistance (1/Rp) is the sum of the reciprocals of individual resistances. 1/Rp = 1/R1 + 1/R2 + 1/R3 = 1/2 + 1/3 + 1/6. Finding a common denominator (6): 1/Rp = 3/6 + 2/6 + 1/6 = 6/6 = 1. Therefore, Rp = 1 Ω.
This question belongs to: Science Physics
Question #43
According to Joule's law of heating, the heat produced in a resistor is directly proportional to the square of:
A. Time
B. Resistance
C. Electric Current
D. Voltage
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Correct Answer: Option C

Explanation:
Joule's Law of Heating states that the heat (H) produced in a resistor is given by H = I²Rt. This indicates that the heat produced is directly proportional to the square of the electric current (I), directly proportional to the resistance (R), and directly proportional to the time (t) the current flows.
This question belongs to: Science Physics
Question #44
Assertion (A): A fuse wire must have a high resistance and a low melting point. Reason (R): This ensures it melts quickly and breaks the circuit when an excessively high current flows.
A. Both A and R are true and R is the correct explanation of A.
B. A is true but R is false.
C. Both A and R are true but R is NOT the correct explanation of A.
D. A is false but R is true.
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Correct Answer: Option A

Explanation:
A fuse is a safety device. It must have a relatively high resistance so that it produces heat quickly when a large current passes through (H = I²Rt). It must have a low melting point so that this heat causes it to melt immediately, breaking the circuit and protecting appliances. Thus, both A and R are true, and R explains A.
This question belongs to: Science Physics
Question #45
The direction of the magnetic field lines around a straight current-carrying conductor can be determined by:
A. Right-Hand Thumb Rule
B. Fleming's Left-Hand Rule
C. Fleming's Right-Hand Rule
D. Faraday's Law
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Correct Answer: Option A

Explanation:
Maxwell's Right-Hand Thumb Rule states that if you imagine holding a straight current-carrying conductor in your right hand such that the thumb points in the direction of the current, then the direction in which your fingers wrap around the conductor represents the direction of the circular magnetic field lines.
This question belongs to: Science Physics
Question #46
An electric motor converts:
A. Magnetic energy into electrical energy
B. Mechanical energy into electrical energy
C. Chemical energy into mechanical energy
D. Electrical energy into mechanical energy
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Correct Answer: Option D

Explanation:
An electric motor is a device that utilizes the magnetic effect of electric current. When a current-carrying coil is placed in a magnetic field, it experiences a force (Fleming's Left-Hand Rule) that causes it to rotate. Therefore, it continuously converts electrical energy into mechanical energy. A generator does the reverse.
This question belongs to: Science Physics
Question #47
Alpha particles are fundamentally equivalent to:
A. Helium nuclei
B. High-energy photons
C. Fast-moving electrons
D. Hydrogen nuclei
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Correct Answer: Option A

Explanation:
An alpha particle consists of two protons and two neutrons tightly bound together. This is completely identical to the nucleus of a helium atom (He²⁺). Alpha particles are positively charged, relatively massive, have low penetrating power, and are emitted by heavy radioactive elements during alpha decay.
This question belongs to: Science Physics
Question #48
In a nuclear reactor, what is the function of the moderator (like heavy water or graphite)?
A. To act as the nuclear fuel.
B. To transport heat away from the reactor core.
C. To slow down the fast-moving neutrons so they can cause further fission.
D. To absorb excess neutrons to stop the chain reaction.
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Correct Answer: Option C

Explanation:
Uranium-235 undergoes fission most efficiently when struck by slow-moving (thermal) neutrons. However, fission reactions release very fast-moving neutrons. The moderator (like graphite or heavy water) collides with these fast neutrons to slow them down without absorbing them, sustaining the controlled chain reaction. Control rods (cadmium/boron) are used to absorb excess neutrons.
This question belongs to: Science Physics
Question #49
The energy emitted by the Sun is primarily a result of:
A. Radioactive decay of uranium.
B. Nuclear fusion of hydrogen into helium.
C. Chemical combustion of gases.
D. Nuclear fission of heavy elements.
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Correct Answer: Option B

Explanation:
The Sun and other stars generate their immense energy through nuclear fusion. In the Sun's core, immense gravitational pressure and heat cause hydrogen nuclei (protons) to overcome electrostatic repulsion and fuse together to form helium nuclei. This fusion process releases vast amounts of energy according to Einstein's E=mc².
This question belongs to: Science Physics
Question #50
What is the relationship between the time period (T) and frequency (f) of a wave?
A. T = f²
B. T = f
C. T = 1 / f
D. T = v × f
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Correct Answer: Option C

Explanation:
Frequency (f) is defined as the number of complete oscillations or cycles a wave makes in one second (measured in Hertz). The Time period (T) is the time taken to complete one full oscillation (measured in seconds). They are inversely related: T = 1/f. If a wave has a frequency of 50 Hz, its period is 1/50 seconds.
This question belongs to: Science Physics
Question #51
Which of the following is an example of a longitudinal wave?
A. Sound waves in air
B. Light waves
C. Radio waves
D. Water waves on the surface
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Correct Answer: Option A

Explanation:
In a longitudinal wave, the particles of the medium vibrate back and forth parallel to the direction of wave propagation (creating compressions and rarefactions). Sound waves traveling through air are mechanical longitudinal waves. Light and radio waves are transverse electromagnetic waves, while surface water waves are a combination of both.
This question belongs to: Science Physics
Question #52
If the length of a simple pendulum is quadrupled (increased by a factor of 4), what happens to its time period?
A. It doubles.
B. It is halved.
C. It quadruples.
D. It remains unchanged.
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Correct Answer: Option A

Explanation:
The time period of a simple pendulum is given by T = 2π√(L/g), where L is the length of the string and g is acceleration due to gravity. The time period is directly proportional to the square root of the length (T ∝ √L). If L becomes 4L, the new time period T' = √4 = 2 times the original. It doubles.
This question belongs to: Science Physics
Question #53
A galvanometer can be converted into an ammeter by connecting:
A. A high resistance in parallel
B. A low resistance in parallel
C. A low resistance in series
D. A high resistance in series
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Correct Answer: Option B

Explanation:
An ammeter must have very low resistance so it does not alter the circuit current it is measuring. To convert a sensitive galvanometer into an ammeter, a very low resistance called a 'shunt' is connected in parallel to it. This diverts most of the current away from the delicate galvanometer coil while still allowing a proportional measurement.
This question belongs to: Science Physics
Question #54
A microwave oven heats food primarily by exciting which specific molecules in the food?
A. Fat molecules
B. Carbohydrate molecules
C. Protein molecules
D. Water molecules
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Correct Answer: Option D

Explanation:
Microwave ovens use electromagnetic radiation in the microwave frequency range (usually around 2.45 GHz). Water molecules have a permanent electric dipole moment. The oscillating electric field of the microwaves rapidly forces the water molecules to flip back and forth to align with the field, generating thermal energy via friction and effectively heating the food from within.
This question belongs to: Science Physics
Question #55
Why does food cook faster in a pressure cooker?
A. Increased pressure lowers the boiling point of water.
B. The metal of the cooker conducts heat much faster.
C. Increased pressure raises the boiling point of water.
D. The trapped steam adds extra heat directly to the food.
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Correct Answer: Option C

Explanation:
In an open vessel, water boils at 100°C, and extra heat merely creates steam rather than raising the temperature. A pressure cooker traps steam, increasing the internal pressure above atmospheric pressure. Increased pressure raises the boiling point of water (often to around 120°C). Cooking the food at this higher temperature significantly reduces cooking time.
This question belongs to: Science Physics
Question #56
Who is credited with the discovery of the electron?
A. J. J. Thomson
B. Ernest Rutherford
C. James Chadwick
D. Niels Bohr
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Correct Answer: Option A

Explanation:
J. J. Thomson discovered the electron in 1897 through his experiments with cathode ray tubes. He demonstrated that cathode rays were actually streams of negatively charged subatomic particles, much smaller than atoms. Rutherford is famous for discovering the nucleus (gold foil experiment), Chadwick discovered the neutron, and Bohr developed the planetary model of the atom.
This question belongs to: Science Physics
Question #57
The Nobel Prize in Physics in 1930 was awarded to an Indian scientist for his work on the scattering of light. Identify the scientist.
A. Homi J. Bhabha
B. C. V. Raman
C. Meghnad Saha
D. Satyendra Nath Bose
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Correct Answer: Option B

Explanation:
Sir C. V. Raman was awarded the Nobel Prize in Physics in 1930 for discovering the 'Raman Effect'. The Raman effect involves the inelastic scattering of photons by molecules, resulting in a change in wavelength. This discovery proved that light has particle-like characteristics. National Science Day in India (Feb 28) commemorates this discovery.
This question belongs to: Science Physics
Question #58
Two parallel wires carrying direct currents in the opposite directions will:
A. Repel each other
B. Rotate perpendicular to each other
C. Have no effect on each other
D. Attract each other
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Correct Answer: Option A

Explanation:
According to Ampere's force law, parallel wires carrying currents in the SAME direction create magnetic fields that attract each other. Conversely, parallel wires carrying currents in OPPOSITE directions create magnetic fields that push against each other, causing the wires to repel. Exam tip: 'Same' Attracts, 'Opposite' Repels (reverse of charges!).
This question belongs to: Science Physics
Question #59
The concept of 'Inertia' was first practically developed by which scientist before Newton incorporated it into his First Law?
A. Archimedes
B. Johannes Kepler
C. Galileo Galilei
D. Aristotle
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Correct Answer: Option C

Explanation:
Galileo Galilei conducted experiments rolling balls down inclined planes and concluded that an object in motion would continue moving indefinitely on a frictionless surface. This completely challenged Aristotelian mechanics and formulated the concept of inertia, which Isaac Newton later formalized as his First Law of Motion.
This question belongs to: Science Physics
Question #60
A boy is sitting on a rotating chair with his arms folded. If he suddenly extends his arms, what will happen to his angular velocity?
A. It will become zero.
B. It will increase.
C. It will decrease.
D. It will remain the same.
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Correct Answer: Option C

Explanation:
This is based on the conservation of angular momentum (L = Iω), where 'I' is the moment of inertia and 'ω' is angular velocity. When the boy extends his arms, mass moves further from the axis of rotation, increasing his moment of inertia (I). Since 'L' is conserved, an increase in 'I' must result in a decrease in angular velocity (ω).
This question belongs to: Science Physics

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