Class 12 Physics Model Question Solution 2079 Set I

Greetings, dear students! As you gear up for your upcoming board examinations, we understand the mixture of excitement and nervousness that you might be feeling. These exams are a significant milestone in your academic journey, and we're here to lend a helping hand. In this article, we present to you the comprehensive solutions for the Class 12 Physics Model Question of 2079, Set I. We understand that tackling physics questions can sometimes be a bit tricky, but fret not! Our detailed solutions are tailored to simplify complex concepts and provide you with a step-by-step understanding of each problem. Whether you're revising key concepts or seeking clarity on particular questions, this resource aims to equip you with the knowledge and confidence needed to excel in your physics board exam. So, let's dive into the world of physics problem-solving and pave the way for your success!

2.a)ans: The acceleration of a particle executing Simple Harmonic Motion (SHM) is directly proportional to the displacement of the particle from its mean position.

For mean position acceleration is minimum. So, At the mean position, the acceleration is zero since there is no displacement.

For Q.no 10.

Physics Model Question- 2079 (Class 12) Set-I 

Questions

1. a. Define Capillarity

b. Water rises in a capillary tube while mercury falls in the same tube, why?

c. Water rises ina capillary tube to a height of 2 cm. In another capillary tube whose radius is one-third of it, how much the water will rise?

2. a. How is the acceleration of a particle executing SHM related to its displacement from mean position?

b. An atom of a crystal vibrates with SHM with frequency 10^14 Hz. The amplitude of motion is 2.0*10^12m. Calculate the time period of vibration and maximum velocity of the atom. Sketch the graph to show how the displacement of atoms varies during one cycle.

c. If the pendulum clock is kept in an elevator falling freely. Does it give the correct time?

Or

a. Define moment of inertia.

b. Derive an expression for rotational kinetic energy.

c. The moments of inertia of two rotating bodies A and B about the same axis are Ia and Ib (Ia>Ib) and their angular momentum are equal. Which has greater rotational kinetic energy?

3. a State and prove Brewster's law.

b. Is polarization possible for longitudinal waves? Why?

4. a State the first law of thermodynamics.

b. For the same heat supplied, the rise in temperature of gas is high when it is heated at constant volume than at constant pressure. why?

c. A system is taken from state 'a' to 'b' along three paths. Along which path the work done by the system is greatest and least. Give a reason.

5. a Obtain the balanced condition for Wheatstone Bridge?

b. Wheatstone bridge is not suitable for measuring very low resistance. Why?

6 a. State and explain Lenz's Law of electromagnetic induction.

b. The inductance coils are made of coppery. Why?

c. A 0.5m long metal rod PQ completes the circuit as shown in the figure. The area of the circuit is perpendicular to the magnetic field of flux density 0.15T. If the resistance of the total circuit is 3 ohm, calculate the force to move the rod in the direction as indicated with a constant speed of 2m/s.

7 a. The value of e/m is constant for cathode rays, but not for positive rays. Explain.

b. An electron moves in a circular path of radius 20cm in a magnetic field of 2*10^-3T, Find the speed of electrons. What is the potential through which electron must be accelerated to acquire this speed?

8. a Define photoelectric effect.

b. Can all photons eject electrons from a material? Explain.

c. What would be the minimum work function for metal have to be visible light 400nm to 700nm to eject photoelectron?