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Power of a lens = \(\frac{1}{f}\) f = focal length f = \(\frac{1}{p}\) = \(\frac{1}{5}\) = 0.2m

From Hoke's Law, F = ke, K = Constant of Force For he first case, Force = mg, = 0.8 × 10 = 8N ∴ 8 = k × 0.04 k = \(\frac{8}{0.04}\) = \(\frac{200N}{m}\) Since K is constant For the second case, F = ke F = 200 × e ∴ e = \(\frac{F}{200}\) = \(\frac{16}{200}\) = 0.08m

Eddy currents are produced by the varying flux cathode, the iron core of an equipment thus reducing efficiency due to power consumption. It can be reduced by laminating the core by breaking up the path of eddy current or by increasing the resistance of the core Usage of insulated soft iron wire is to reduce hysteresis loss Usage of low resistance wire (thick wire) is to reduce I2R loss Usage of thick wire is to reduce leakage heat loss due to leakage of magnetic flux Thus the correct answer is to use high resistance wire or thin wire

c = 8µF, v = 10v Energy stored = \(\frac{1}{2}\) cv2 = \(\frac{1}{2}\) × (8 × 10− 6) × 102 = 4 × 10\(^{-4}\)

Impulse = momentum Impulse = Force (f) \times time (t) Momentum = mass (m) \times velocity (v) ∴ Ft = Final momentum - initial momentum FT = mv - mu Since it is initially at rest u = 0 ∴ 5 \times 5 = mv − m(0) 25 = mv ∴ Final momentum = 25kgms\(^{-1}\)

Refraction, Interference and diffraction are all properties of waves

About electric cell Primary cells are used up gradually often the cells are use and it can't be recharged Secondary cells or accumulated can be recharged and used for a long period of time and their main advantage is that they have low internal resistance

Semi-conductor have an elecctric conductivity intermediate in value between that of a pure metal and a good insulator. Silicon is an example

A black solution is a better radiator of heat and allow a better absorber of heat.

Nucleus of atom is made up of neutron and proton

Thermometer is used to measure temperature Hydrometer is used to measure relative density of liquid. Spring balance is used to measure the weight of an object Beaker is used to measure or take volume of a liquid

1 cycle = 360^\circ = 2\pi rad ∴ 50 cycle = 2 \pi rad \times 50 = 100 \pirad ∴ = angular speed = 50 cycles per seconds = 100 \pi rads\(_{−1}\)

Capillarity is the tendency of a liquid to rise or fall in a narrow tube and it explains why a blotting paper absorbs ink

When two mirror are inclined at an angle \theta, the number of images formed, n = \(\frac{360}{\theta}\) − 1 ∴ since \(\theta\) = 90o ∴ \(\frac{360}{\theta}\) − 1 = 4 − 1 = 3

When silicon is doped with a trivalent atom. A p-type semi-conductor will be formed when silicon is doped with a pentavalent atom such as arsenic, a n-type semi-conductor will be formed Phosphorous is a pentavalent element, so it will produce a o -type semi-conductor