Question Library

Thermonuclear fusion is the process that occurs when two atoms combine to make a larger atom, creating a whole lot of energy. Fusion already happens naturally in stars — including the sun — when intense pressure and heat fuse hydrogen atoms together, generating helium and energy. Thermionic emission: thermally induced flow of charge Nuclear fission: nuclear reaction or a radioactive decay process Photoelectric emission: emission of electrons or other free carriers when light shines on a material

Y – Ray is a penetrating electro-magnetic radiation. \alpha – particle is produced in the process of alpha decay. Neutron is a sub-atomic particle.

Radiation refers to the transmission of energy as electromagnetic radiation from its emission at a heated surface to its absorption on another surface, a process requiring no medium to convey the energy. Conduction is the transferring of heat by direct contact. Convection is transferring heat through the motions of fluids (gases and liquids).

Conduction: the flow of internal energy from a region of higher temperature to lower temperature Convection: heat transfer due to bulk movement of molecules within fluids Expansion: the action of becoming larger or more extensive

Viscosity, resistance of a fluid (liquid or gas) to a change in shape, or movement of neighboring portions relative to one another. Viscosity denotes opposition to flow. The reciprocal of the viscosity is called the fluidity, a measure of the ease of flow. Molasses, for example, has a greater viscosity than water. Because part of a fluid that is forced to move carries along to some extent adjacent parts, viscosity may be thought of as internal friction between the molecules; such friction opposes the development of velocity differences within a fluid. Viscosity is a major factor in determining the forces that must be overcome when fluids are used in lubrication and transported in pipelines. It controls the liquid flow in such processes as spraying, injection molding, and surface coating.

No expanded working has been attached for this question yet. The verified answer is Option B.

P = F \times \(\frac{S}{1}\) P = F x V F = \(\frac{P}{V}\)

Pressure = \(\frac{Force}{Area}\) Pressure = m \times \(\frac{a}{t}\) = \(\frac{MLT^{−2}}{L \times L}\) = ML\(^{−1}\)T\(^{−2}\)

If a liquid is heated the particles are given more energy and move faster and faster expanding the liquid.The result is that liquids show a reduction in viscosity with increasing temperature. With high temperatures, viscosity increases in gases and decreases in liquids, the drag force will do the same.

Impulse = Change in momentum m (v - u) 5 (2.0) = 5 x 2 = 10.0kgm\(^{-1}\) = 10.0kgms\(^{-1}\)

Weight of water displaced = upthrust = 30 - 21 = 9N Mass of water displaced = \(\frac{9}{10}\) = 0.9kg Volume of object = 9 \times 10\(^{-4}\)m\(^3\) = (9 \times 10\(^{-4}\)) (1.4 \times103) = 1.26kg = 12N 30 - 12.6 = 17.4N

No expanded working has been attached for this question yet. The verified answer is Option A.

The primary reason that power is transmitted at high voltages is to increase efficiency. As electricity is transmitted over long distances, there are inherent energy losses along the way. High voltage transmission minimizes the amount of power lost as electricity flows from one location to the next. How? The higher the voltage, the lower the current. The lower the current, the lower the resistance losses in the conductors. And when resistance losses are low, energy losses are low also. Electrical engineers consider factors such as the power being transmitted and the distance required for transmission when determining the optimal transmission voltage

Focal length: \( f = 20 \, \text{cm} \) Object distance: \( u = 100 \, \text{cm} \) (positive since it's in front of the lens) \end{itemize} Using the lens formula: \(\frac{1}{f} = \frac{1}{v} + \frac{1}{u}\) Substituting the known values: \(\frac{1}{20} = \frac{1}{v} + \frac{1}{100}\) Rearranging to solve for \( v \): \(\frac{1}{v} = \frac{1}{20} - \frac{1}{100}\) Finding a common denominator (100): \(\frac{1}{20} = \frac{5}{100}\) Thus, \(\frac{1}{v} = \frac{5}{100} - \frac{1}{100} = \frac{4}{100}\) Solving for \( v \): \(v = \frac{100}{4}\) = 25 cm

F= 15cm M = 3 M = \(\frac{v}{u}\) V =3u \(\frac{1}{f}\) = \(\frac{1}{u}\) + \(\frac{1}{v}\) \(\frac{1}{15}\) = \(\frac{1}{u}\) - \(\frac{1}{3u}\) \(\frac{1}{15}\) = \(\frac{2}{3u}\) U =10cm D = u + v = 10 +30 = 40cm