12th Physics One Mark Questions With Answers PDF

Understanding and preparing for 12th-grade physics can be challenging, especially with competitive exams approaching. This compilation of one-mark questions with answers is designed to strengthen your grasp of fundamental concepts. It is structured for easy revision, ensuring students can practice effectively and gain confidence in solving physics problems.

12th Physics One Mark Questions with Answers

Question: What is the SI unit of force?

Answer: Newton (N)

Question: State Newton’s first law of motion.

Answer: A body remains at rest or in uniform motion unless acted upon by an external force.

Question: Define acceleration.

Answer: Acceleration is the rate of change of velocity with respect to time.

Question: What is the value of gravitational constant (G)?

Answer: 6.674×10−11Nm2/kg26.674 × 10^{-11} N m^2/kg^26.674×10−11Nm2/kg2

Question: What is the dimensional formula of energy?

Answer: [ML2T−2][ML^2T^{-2}][ML2T−2]

Question: Which physical quantity is represented by the area under a velocity-time graph?

Answer: Displacement

Question: Define momentum.

Answer: Momentum is the product of mass and velocity of an object.

Question: What is the speed of light in a vacuum?

Answer: 3×108 m/s3 × 10^8 \, m/s3×108m/s

Question: State Ohm’s Law.

Answer: The current through a conductor is directly proportional to the voltage across it, provided temperature remains constant.

Question: What is the SI unit of charge?

Answer: Coulomb (C)

Question: What is the function of a fuse in an electric circuit?

Answer: A fuse protects the circuit by breaking the connection when excessive current flows through it.

Question: Define power in terms of physics.

Answer: Power is the rate at which work is done or energy is transferred.

Question: What is the formula for kinetic energy?

Answer: KE=12mv2KE = \frac{1}{2} mv^2KE=21​mv2, where $m$ is mass and $v$ is velocity.

Question: What is the unit of magnetic field strength?

Answer: Tesla (T)

Question: Define refractive index.

Answer: Refractive index is the ratio of the speed of light in a vacuum to the speed of light in a medium.

Question: What is the wavelength of visible light?

Answer: 400 nm to 700 nm

Question: What is Hooke’s Law?

Answer: Stress is directly proportional to strain within the elastic limit.

Question: Name the device used to measure electric current.

Answer: Ammeter

Question: State the principle of conservation of energy.

Answer: Energy can neither be created nor destroyed; it can only change from one form to another.

Question: What is the SI unit of frequency?

Answer: Hertz (Hz)

Question: Define work in physics.

Answer: Work is done when a force is applied to an object and the object is displaced in the direction of the force.

Question: What is the unit of electric potential?

Answer: Volt (V)

Question: Define capacitance.

Answer: Capacitance is the ability of a system to store an electric charge.

Question: What is the critical angle?

Answer: The critical angle is the angle of incidence for which the angle of refraction is 90∘90^\circ90∘.

Question: What is the formula for potential energy?

Answer: $PE=mgh$, where $m$ is mass, $g$ is acceleration due to gravity, and $h$ is height.

Question: State the second law of thermodynamics.

Answer: Heat energy cannot spontaneously transfer from a cooler body to a hotter body without external work.

Question: What is the charge of an electron?

Answer: −1.6×10−19C -1.6 × 10^{-19} C−1.6×10−19C

Question: Define angular velocity.

Answer: Angular velocity is the rate of change of angular displacement with respect to time.

Question: What is the principle of a transformer?

Answer: A transformer works on the principle of electromagnetic induction.

Question: Define half-life in radioactivity.

Answer: Half-life is the time required for half the nuclei in a radioactive sample to decay.

Question: What is the formula for the magnification of a lens?

Answer: M=Image heightObject heightM = \frac{\text{Image height}}{\text{Object height}}M=Object heightImage height​

Question: State the law of reflection.

Answer: The angle of incidence is equal to the angle of reflection.

Question: What is meant by a uniform circular motion?

Answer: Motion in a circular path with constant speed is called uniform circular motion.

Question: Define escape velocity.

Answer: Escape velocity is the minimum velocity required for an object to escape Earth’s gravitational pull.

Question: What is the formula for current in terms of charge?

Answer: I=QtI = \frac{Q}{t}I=tQ​, where $I$ is current, $Q$ is charge, and $t$ is time.

Question: State Coulomb’s law.

Answer: The force between two charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.

Question: Define drift velocity.

Answer: Drift velocity is the average velocity attained by charged particles in a conductor due to an electric field.

Question: What is the unit of resistance?

Answer: Ohm ($\Omega$)

Question: Name the law that gives the emf induced in a coil.

Answer: Faraday’s Law of Electromagnetic Induction

Question: What is the principle of superposition of waves?

Answer: When two or more waves overlap, the resultant displacement is the algebraic sum of the displacements of individual waves.

Question: What is the formula for the refractive index?

Answer: n=cvn = \frac{c}{v}n=vc​, where $c$ is the speed of light in a vacuum, and $v$ is the speed of light in the medium.

Question: What is the purpose of a galvanometer?

Answer: A galvanometer detects and measures small electric currents.

Question: State the formula for resistance in a parallel circuit.

Answer: 1R=1R1+1R2+…\frac{1}{R} = \frac{1}{R_1} + \frac{1}{R_2} + \dotsR1​=R1​1​+R2​1​+…

Question: Define thermal conductivity.

Answer: Thermal conductivity is the property of a material to conduct heat.

These one-mark physics questions and answers are an excellent resource for students preparing for 12th-grade exams. They cover key topics concisely and ensure thorough revision of important concepts. Regular practice will enhance understanding and boost confidence for exams, making complex topics easier to master.