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The energy supplied by the heater = heater gained by the water pt = Mc\(\Delta\)\theta 1000 x 300 = m x 4200(100 - 30) m = \(\frac{(1000 \times 300)}{4200 \times 70}\) = 1.02 kg

F ∝ \(\frac{M_1 M_2}{r^2}\) F = \(\frac{GM_1M_2}{r^2}\) where F is the force of attraction M\(_1\) and M\(_2\) are the masses of the two bodies, r is the distance between them, and G is the universal gravitational constant Therefore, G = \(\frac{Fr^2}{M_1M_2}\) Dimension for F = \(\frac{\text{ML}}{T.T}\) = MLT\(^{-2}\) The dimension for G = \(\frac{MLT^{-2}L^2}{M.M}\) = \(\frac{L^3T^{-2}}{M}\) = M\(^{-1}\)L\(^3\)T\(^{-2}\) In comparison with M\(^x\)L\(^y\)T\(^z\), the values for x, y and z = -1, 3, -2

The leaves collapse as the positive charges on the rod neutralize the negative charges on the electroscope.

The electric potential at a point in an electric field is defined as the amount of work done in moving a unit positive charge from infinity to that point against the action of the field. V = \(\frac{Q}{4 \pi∈r}\)

1/R = 1/R1 + 1/R2 = 1/3 + 1/6 = 3/6 ∴ R = 6/3 = 2 E = I(R + r) = 4(2 + 0) = 8v

V = \sqrt \({(v_l - v_c)}^2 + V^2R\) V =\sqrt \({(40 - 110)}^2 + 80^2\) V = \sqrt \({-70}^2 + 80^2\) =\sqrt 4900 + 6400 =\sqrt 11300 = 106.3v

Thermionic emission is ejection of electron from a metal surface as a result of heating.

Metals are good conductors due to the presence of free electrons.

When a pentavalent (5 outer electron)atom is added to a pure semiconductor, there is an extra electrons which does not take part in the covalent bonding resulting in an n-type semiconductor.

Canorous cells can be destroyed with a high penetrating radiation which is x - rays

Half-life, T (1)/2 = (0.693)/∆ = (0.693)/ 0.231 = 3.0sec

The number of disintegration,∆N in time interval At, is given by - ∆N = N∆t Where N is the number of atoms present at the time t But ^ = (0.693)/T = 0.693 \div 20 = 0.0347 ∴ ∆N = 0.0347 \(\times\) 10\(^20\) = 3.47 \(\times\) 10\(^18\)

The equation above is Beta-decay: where \beta is an electron → \(^{0} _{-1}e\) 2\beta in the equation = \(^{0} _{-1}e\) + \(^{0} _{-1}e\) → \(^{0} _{-2}e\) \(^{222}_{86}Rn\) → \(^{x}_{88}Ra\) + \(^{0} _{-2}e\) + energy where \(^{x}_{88}Ra\) + \(^{0} _{-2}e\) → \(^{222}_{86}Rn\) : x = 222 for element Radon [ \(^{222}_{88}Ra\)

The process of energy production in the sun is generally by nuclear fusion of hydrogen nuclei, the reaction of which takes place at a tremendous high temperature.

The sun and stars are self luminous object.