575 - Physics Questions Answers
Two absolute scales A and B have triple points of water defined to be 200 A and 350 B. What is the relation between Ta and Tb?
(1) Ta = Tb/2
(2) Ta = 7Tb/4
(3) Ta = 2Tb
(4) Ta = 4Tb/7
273.15 K = 200 A
and 273.15 K = 350 B
so A = 273.15 K/200 and B = 273.15 K/350
so Ta A = TbB
or Ta/Tb = B/A = 200/350 = 4/7
so 4th option
The absolute zero temperature is
(1) -273° C
(2) -273.15 K
(3) -273.15° F
(4) -273.15° C
it is -273.15 0C
2 moles of a diatomic gas are enclosed in a vessel. when a certain amount of heat is supplied, 50% of the gas molecules get dissociated, bit there is no rise in temperature. What is the heat supplied if the temperature is T?
(1) RT
(2) RT/2
(3) 11RT/2
(4) 5RT
internal energy of 2 mole diatomic gas = 2*5/2 RT = 5RT
now after 50% disociation in monoatomic form total internal energy
of 1 mole diatomic gas = 1*5/2 RT = 2.5 RT
and that of 2 mole monoatomic = 2*3/2 RT = 3RT ( 2 mole monoatomic gas will be formed by the dissociation of 1 mole diatomic gas)
so internal energy change = 1/2 RT
This internal energy increment will be equal to the heat provided
A gaseous mixture consists of 16g of helium and 16g of oxygen. the ratio Cp/Cv of the mixture is
(1) 1.59
(2) 1.62
(3) 1.4
(4) 1.54
16 gms He = 4 mole, 16 gms O2= 1/2 mole
so total freedom n = [4(3) + 1/2(5)] / [4 + 1/2] = 3.22222 here 3 and 5 are freedoms for mono and di atomic gases
so γ = 1 + 2/3.2222222 = 1.621
A vessel of volume 0.3 m³ contains helium at 20.0°C. the average kinetic energy per molecule for the gas is
(1) 6.07 * 10^(-21) J
(2) 7.3 * 10³ J
(3) 14.6 * 10³ J
(4) 12.14 * 10^(-21) J
Use the formula 3/2 kT
k is boltzmann constant = 1.38* 10-23
4 moles of an ideal monoatomic gas is mixed with 6 moles of a non reactive diatomic ideal gas. the molar heat capacity of the mixture at constant volume is (assume no vibration) nearly
(1) 27 J mol‾¹K‾¹
(2) 17 J mol‾¹K‾¹
(3) 7 J mol‾¹K‾¹
(4) 37 J mol‾¹K‾¹
at constant volume work done = 0
degree of freedom = 4(3) + 6(5) / 4 + 6 = 12+30/10 = 4.2 so γ = 1 + (2/4.2)
so molar heat capacity = R/(γ-1)
consider an ideal gas contained in a vessel. if the intermolecular interaction suddenly beings to act, which of the following will happen?
(1) the pressure decreases
(2) the pressure increases
(3) the pressure remain unchanged
(4) the gas collapses
if the intermolecular interaction suddenly beings to act, then the pressure increases because due to intermolecular interaction gase will work as real gas
in the previous case if north pole is brought near the mettalic ring why the direction is reversed. we have to consider the drn of magnetic field of magnet or not. if yes then which drn N-S or S-N.
The south pole of a magnet is bought near a metallic ring ,the direction induced current in the ring will be? Explain it clearly.
If observer is in the side of magnet, then in the given case form S in the ring, it will give you clockwise direction
can you give me an idea of solving the parallel LC circuit? Also to find the phase difference between the I and E?
1st make a 3 line circuit in which ac source, resistor with an inductor and resistor with a capacitor will be there in the three lines then divide total current "I"
from AC into the two legs, equations will be
e = L di1/dt + i1R (1)
e =q2 / C + i2 R (2) here dq2 / dt = i2
now solve