Physics MCQs for NEET — Practice Questions with Answers

If the coefficient of volume expansion and raise in temprature is $ \triangle \theta $ then $ \triangle v = v \alpha \triangle \theta $ $ \Rightarrow { \triangle v \over v } = \alpha \triangle \theta $ volume elasticity $ \beta = { P \over { \triangle v \over v }} = { P \over \alpha \triangle \theta } $

If side of the cube is L then V =$ L^ 2$ $$ \Rightarrow { dv \over v } = { 3dL \over L } $$ $ \% change in voulume = 3 \times (\% change in length) = 3 \times 1\% = 3\% $ $ \therefoe Bulk modulus = { \triangle v \over v } = 0.03 $

$ Adiabatic elasticity \varepsilon = vp $ $ For Argon EA_r = 1.6 p$ $For hydrogon EH_2 = 1.4 pl$ As elasticityof hydrogen & Argon are equal $ \therefore 1.6 P = 1.4 Pl $ $ \therefore P' = 8/7 P $

Isothermal elasticity P = Ki = 1 atm = 1.013 = $ 1.013 \times 10^5 N/m^2 $

Isothermal bulk modulus = pressure of gas

$$ {dv \over v } = ( 1 + 2 \sigma) {dL \over L } $$ $\therefore {dv \over v } = 2 \times 2 \times 10^{-3} = 4 \times 10 ^ {-3} $ $ [ 6 = 0.5 { 1 \over 2 } ] $

we know that $ {dv \over v } = (1 - 2 \sigma) { dL \over L } $ $ if \sigma = {1 \over 2 } then { dv \over v } = 0 $ i.e. there is no change in volume

$ Y = 2N ( 1 + \sigma) $

$ Y = 2n ( 1 + \sigma) \Rightarrow \sigma = { 0.5 y - n \over n } $

Twisting couple C = $ { \pi n r^4 \over 2l } \theta $ If material and length of the wires Aand B equal twisting coulple are applied then $ \theta \alpha {1 \over r^4 } $ $ \therefore { \theta_1 \over \theta_2 } = \left( {r_2 \over r_1} \right)^4 $