NEB Class 12 Science Physics Question Paper 2080

NEB Class 12SCIENCEfirst-terminal

40marks

90min

13questions

This is the official NEB Class 12 (Science stream) Physics (भौतिक शास्त्र) question paper for 2080, as set in the first-terminal first-terminal examination. It carries 40 full marks and a time allowance of 90 minutes, across 13 questions. On Kekkei you can attempt this Physics past paper online with a timer, get instant AI feedback and step-by-step solutions, and track the topics where you lose marks — completely free. Whether you are revising for your NEB Class 12 Physics exam or solving previous years' question papers, this 2080 paper is a great way to practise under real exam conditions.

Group 'A'

Rewrite the correct options of each question in your answer sheet.

7 questions·1 marks each

1mcq1 marks

For the photoelectric effect in sodium, the figure shows the plot of cut-off voltage versus frequency of incident radiation. The threshold frequency is

Plot of cut-off voltage versus frequency for photoelectric effect in sodium

a
$1\times10^{14}\,\text{Hz}$
b
$2\times10^{14}\,\text{Hz}$
c
$3\times10^{14}\,\text{Hz}$
d
$4\times10^{14}\,\text{Hz}$

photoelectric-effectthreshold-frequency

2mcq1 marks

The moment of momentum is called

a
Couple
b
Torque
c
Impulse
d
Angular momentum

rotational-motionangular-momentum

3mcq1 marks

The temperature of inversion of a thermocouple is 700°C and the neutral temperature is 365°C. Then, the temperature of cold junction must be

a
$0^\circ\text{C}$
b
$30^\circ\text{C}$
c
$35^\circ\text{C}$
d
$65^\circ\text{C}$

thermoelectricitythermocouple

4mcq1 marks

When a gas undergoes adiabatic expansion, its internal energy

a
Increases
b
Decreases
c
Remains same
d
None

thermodynamicsadiabatic-expansion

5mcq1 marks

Two waves are $y=a\sin(\omega t-kx)$ and $y=a\cos(\omega t-kx)$ . Now, the phase difference between the two waves is

a
$\pi/2$
b
$\pi/4$
c
$\pi$
d
Zero

wave-motionphase-difference

6mcq1 marks

The emf of a battery A is balanced by a length of 75 cm on a potentiometer wire. The standard cell of emf 1.02 V is balanced by a length of 50 cm. The emf of a cell is

a
$1.25\,\text{V}$
b
$1.35\,\text{V}$
c
$1.53\,\text{V}$
d
$2.05\,\text{V}$

current-electricitypotentiometer

7mcq1 marks

The efficiency of Carnot's Cycle is independent of

a
Working Substance
b
Temperature of Source
c
Temperature of Sink
d
All of Above

thermodynamicscarnot-cycle

Group 'B'

6 questions·5 marks each

8short5 marks

a) An electron and a proton enter in a transverse electric field with the same velocity. Which particle has more curved trajectory? Explain. [2]

b) An electron moving with a speed of $10^{7}\,\text{m/s}$ is passed into a magnetic field of intensity 0.1 T. What is the radius of the path of the electron inside the field? (Given: $e/m=1.8\times10^{11}\,\text{C/Kg}$ ) [3]

electric-fieldmagnetic-fieldcharged-particle-dynamics

9short5 marks

a) What do you mean by cyclic process? [1]

b) How the heat and thermodynamic process is useful in our daily life? Explain. [1]

c) A gas in a cylinder is initially at a temperature of 17°C and pressure $1.01\times10^{5}\,\text{N/m}^{2}$ . If it is compressed adiabatically to one-eighth of its original volume, what would be the final temperature and pressure of the gas? [3]

a) Spark plug is not necessary in a diesel engine. Why? [2]

b) The figure represents the PV-diagram of different stages of a thermodynamic process. Calculate the work done in each stage and the net work done in the complete cyclic process.

PV diagram showing a cyclic rectangular path ABCD [3]

thermodynamicscyclic-processadiabatic-compressionpv-diagram

10short5 marks

a) What do you mean by rigid body? [1]

b) How does angular velocity differ from the linear velocity? [1]

c) Derive an expression for the Moment of Inertia of a uniform rod about an axis through its centre and perpendicular to its length. [3]

rotational-dynamicsrigid-bodyangular-velocitymoment-of-inertia

11short5 marks

a) Why the connections between the resistors in a meter bridge are made of thick copper strips? [1]

b) Why is it generally preferred to obtain the balance length near the mid-point of the bridge wire? [1]

c) Calculate the potential difference between the 4Ω resistor in the given electrical circuit.

Circuit diagram containing two voltage sources 8V and 6V with two loops [3]

current-electricitymeter-bridgekirchhoffs-laws

12short5 marks

a) How transverse wave is different from longitudinal wave? [1]

b) Derive the Newton's formula for the velocity of sound. [2]

c) What correction was made by Laplace? Explain. [2]

wave-motionvelocity-of-soundlaplace-correction

13short5 marks

a) Draw the magnetic field lines for the current carrying solenoid. [1]

b) State and explain the Biot and Savart law. Use this law to calculate the magnetic field at the centre of a current carrying circular coil. [2]

c) A 60 cm long wire of mass 10 gm is suspended horizontally in a transverse magnetic field of flux density 0.4 T through two springs at its two ends. Calculate the current required to pass through the wire so that there is zero tension in the springs. [2]

magnetic-fieldbiot-savart-lawmagnetic-force