(iii) A consequence of the Free Electron approach is that the electron mass me effectively becomes a variable, the so-called effective mass, me * , which is governed by the curvature of the Ek vs. k function. Show that where the curvature of this function is large the effective mass is small. [4 marks]

(iv) It is often found that some ‘useful’ semiconductors such as silicon or gallium arsenide have bands which show a high degree of curvature, whereas many insulators do not. Discuss how this influences the properties of each type of material.

Answer it in detail (1-2 paragraphs)

1. Define a reference frame and then an inertial reference frame. Give example of both inertial and non-inertial reference frames.

2. Explain the concept of time dilation. What is the twin paradox?

3. Explain why it is impossible for an object to travel at the speed of light (Hint: evaluate the energy of the object)

4. Discuss the importance of the photoelectric effect in the context of quantum physics.

5. What is the de Broglie wavelength? List at least one experimental evidence the matter exhibits wave characteristics.

6. State Hesisenberg's uncertainty principle.

For higher accuracy, should R decade be large or small? Why?

Explain why there is more danger when you fall and bounce as opposed to falling without bouncing.

Laser light from argon ion laser of wavelength 488.0 nm passes through a diffraction grating. The first bright spots occur at an angle 6.726 degree left and right from the central maximum. How many additional pares of bright spots are there beyond the first bright spots?

The solar wind consists of protons, electrons and other heavier irons and they have velocities of several hundred km per second. Moving charged particles experience a force when in an external magnetic field. The Earth's magnetic field at the equator has a value of approximately 3 x 10^-5 T and is directed to the north. This field strength extends into the space above the earth. Consider a solar wind proton moving at 5 x 10⁵ m/s that approaches the earth from outer space along a line toward the center of the earth that lies on the plane of the equator. In what direction will the proton be deflected? Will it reach the earth's surface? What if the particle were an electron? Why is the Earth's Magnetic field important to life on the Earth?

A converging lens has a focal length of 9.0 cm. Locate the images for the object distances of (a) 20.0 cm, (b) 10.0 cm, and (c) 5.00 cm, if they exist. For each case, state whether the image is real or virtual, upright or inverted, and find the magnification.

An 90mm focal-length lens is used to focus an image on the film of a camera. The maximum distance allowed between the lens and the film plane is 130mm .

A. How far ahead of the film should the lens be if the object to be photographed is 2.9

m away?

B. How far ahead of the film should the lens be if the object to be photographed is 1.1

m away?

C. What is the closest object this lens could photograph sharply?

describe how you can use a magnet to exert both a contact force and a non-contact force on another magnet?

A family comes home from a long vacation with laundry to do and showers to take. The water heater has been turned off during vacation. If the water heater has a capacity of 49.1 gallons and a 4610 W heating element, how much time is required to raise the temperature of the water from 18.8°C to 62.1°C? Assume that the heater is well insulated and no water is withdrawn from the tank during this time.

The position of a 0.30-kg object attached to a spring is described by x = (0.24 m) cos(0.8πt). (Assume t is in seconds.) (a) Find the amplitude of the motion. 0.24 Correct: Your answer is correct. m (b) Find the spring constant. 1.9 Correct: Your answer is correct. N/m (c) Find the position of the object at t = 0.33 s. 0.16 Correct: Your answer is correct. m (d) Find the object's speed at t = 0.33 s. Incorrect: Your answer is incorrect.

A bomb at rest at the origin of an xy-coordinate system explodes into three pieces. Just after the explosion, one piece, of mass 4 kg, moves with a velocity of 45 m/s in the negative x-direction, and a second piece, also of mass 4 kg, moves with a velocity of 36 m/s in the negative y-direction. The third piece has a mass of 7 kg.

What is the initial momentum of the bomb before the explosion?

What is the x-component of the velocity of the third piece just after the explosion?

What is the y-component of the velocity of the third piece just after the explosion?

What is the magnitude of the velocity of the third piece?

Just after the explosion, in what direction is the third piece moving? (Give your answer as an angle measured clockwise from the positive x-axis.)

The Millennium Falcon is trying to stay in the Death Star’s blind spot by following a geosynchronous orbit above it. The Falcon is 2.1x10^5m above the surface of the Death Star,

which has a radius of 80 km. The Death Star has a mass of 2.3x10^18 kg and it makes one full rotation about its central axis every 22 hours. What speed does the Falcon need to maintain in order to stay in geosynchronous orbit with the Death Star ?

(Note: there is enough information given in this problem to solve it via two different, independent methods. Try to figure both of them out! They both give the same correct answer.)

Given :Vitrified canister equal 1.5 fuel assemblies (f.p. and MA; Capacity: 155 litres; weight: 490 kg; height: 1.3 m; diameter: 43 cm). An amount ofabout 1 TWh enough for a city of 500k for year takes two canisters.

Assume the average home requires an electrical power of 1.2kW, an average life expectancy of 75 years, and only power from nuclear energy. For such a homeowner, what would be the lifetime generation of vitrified high level waste (HLW) in kg and liters?