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Power supplied = I\(^2\) R = 20\(^2\) X 1 = 400 W Power dissipated = IV = 20 X 220 = 4400 W (Power supplied)/Power dissipated = 4400 W / 400 W = 11 / 1 or 11 : 1

The resistors are in series ∴ Reff = R1 + R2 + ..... = 4 + 4 + 4 + 4 + 4 + 4 = 24 \Omega

Energy consumed = power x time = (60 W x 10 + 40 W x 5) x 24 h = (600 W + 200 W ) x 24 h = 800 W x 24h = 19200 w h = 19.2 kWh

Max kinetic energy = Energy of incident electron - work function. EK = hf - w = 6.6 x 10-34 x 6.7 x 1014 - 3 x 10-19 = 4.422 x 10-19 - 3 x 10-19 = 1.422 x 10-19J

\(\lambda\) = \(\frac{h}{\sqrt{2evm}}\) = \(\frac{6.6 \times 10^{34}}{\sqrt{ 2 \times 1.6 \times 10^{-19} \times 10000 \times 9.1 \times 10^{-31}}}\) = 1.223 x 10\(^{-11}\)m

Zener diode is useful in stabilized power supply i.e to keep steady the voltage of a power supply.

Heating a pure semiconductor increases the mobility of electrons and holes and hence the conductivity. thus, the resistance decreases on heating

Transistor is used for amplification of current, power', voltage stabilization and as a switch in logic gates.

Due to rectilinear propagation of light we have ecslipse which occur as a result relative motion of the earth, sun and moon

Magnification = \(\frac{\text{image height}}{\text{object height}} = \frac{\text{length camera}}{\text{object distance from pin-hole}}\) ∴\(\frac{2}{4} = \frac{6}{X}\) X = \(\frac{4 \times 6}{2}\) = 12 cm

(1)/V + (1)/U = (1)/f (1)/V + (1)/20 = (1)/10 (1)/V = (1)/10 - (1)/20 = (2 -1)/20 = (1)/20 ∴ V = 20 cm mag = (image height)/object height = (v)/u (X)/5 = (20)/50 X = 5 cm

Image formed by convex mirror is always erect, virtual and diminished

Real depth and apparent dept is due to refraction

Magnifications = V/U = 4 ∴ V = 4U 1/V + 1/U = 1/f 1/4u + 1/U = 1/12 5/4U = 1/12 4U = 12 x 5 = 60 ∴ U = 15 cm

Timber/ quality depends on the overtones or harmonics, and timber is a characteristic property of source of sound, A harmonic is a wave with a frequency that is a positive integer multiple of the fundamental frequency, These rest on the fundamental property of FREQUENCY.