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Since 1/32, is the fraction left of any radioactive material after 5half lives, that is: 1/32= (1/2)5. Thus if a half life is 50 days, 5 half lives will be 50 x 5= 250 days

The force acting on a moving charge in the magnetic field is given by: F= qVBSin \theta sin \theta =F=(8.0x10)-14/1.6x10-19x1.0x106x1.0 = (8.0x10)14/16 x 1013 (8.0x 10)-14/16x10-14 =0.5000 ∴ \theta= sin-1 0.5000 =30^\circ

When impurities are added to semi conductor , the semi conductor is said to be doped, and increases the conductivity of the semi-conductor.

The characteristics of a shadow are dependent on the intensity of the light source. A hard light will produce a shadow with a sharp edge, a soft light will produce a shadow with a more blurry edge.

for a real image 3 times the size of the object, it implies that the magnification 3 = v/u, 3 = 24/u, therefore 3u = 24, u = 8cm thus we have from the relation:m = (f)/(u)-f; that 3 = (f)/(8) - f. therefore f = 3(8-f) f = 24 - 3f ∴4f = 24; f = 6cm OR: (1)/(u) + (1)/(v) = (1)/(f). (1)/(8) + (1)/(24) = (1)/(f) therefore (3+1)/(24) = (1)/(f) 4/24=1/f;therefore 4f = 24 f = 6cm

Displacement and torque are vector quantities with both magnitude and direction, while options A, B, and D consist of vector and scalar.

In a wheel and axle system of mechanic, the mechanical advantage is given by its ratio of the radius of the wheel R, to the radius of the axle r. that M.A = R/r

Silicon is a tetra valent (4 valent) element, and in order to produce an n type semi-conductor, it has to be dropped with a penta valent (5valent)element, that, that is element in group five (v)

The electrons and cations of ionized gas act as charge carriers.

The ray which causes gas molecules to fluoresce or glow is the cathode rays

in a transformer, E S/E P = N s/N p where E s=e.m.f(voltage)of the secondary E p=e.m.f(voltage)of the primary N s=no.of turns in the secondary N p= no. of turns in the primary. since E s= V s; and E p= V p. V s/ V p= N s/N p ∴12/240= Ns/4000 Ns =(12x4000)/240 =200

the current in reverse biased junction diode is due to minority carriers, that is, the negative charges in the p-semi-conductor, and the positive charges in the n-semi-conductor.

Sodium is a soft, silvery-white metal that is a good conductor of electricity. It has free-moving electrons, which allows it to conduct electrical current efficiently

When the temperature difference between the wet bulb and dry bulb of a hygrometer is high, it indicates that the air is dry, leading to lower relative humidity. The wet bulb temperature drops more significantly because of evaporation, which occurs more readily in dry air. Conversely, a smaller temperature difference indicates higher humidity.

For liquid W, its mass = vol. x density = 3 x 200 =600kg. similarly, for liquid L, its mass = 7 x 150 = 1050kg ∴ Total mass of mixture = 600kg + 1050kg =1650kg. similarly total vol.of the mixture = 3m3 + 7m3 =10m3. ∴ density of the mixture = (Total Mass)/Total Mixture = (1650kg)/10m3 =165kgm-3