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

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 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.

u = 5 cm , f = 10 cm, v = ? (1)/v + (1)/u = (1)/f (1)/v + (1)/5 = (1)/10 = (1)/v = (1)/10 - (1)/5 = (1 - 2)/10 = (1)/10 ∴ v = - 10 cm ∴ The image is 10 cm behind the mirror

Sin c = (1)/n = (1)/1.51 = 0.6622 ∴ c = sin-\(^1\) 0.6622 = 41.47

The speed of sound is highest in solid. Metals (solids) like copper, steel rod, etc

The quality of a note is a characteristic that distinguishes it from note of the same frequency played by another musical instrument.