If two soap bubbles of different radii are connected by a tube, then
air flows from bigger bubble to the smaller bubble till sizes become equal
air flows from bigger bubble to the smaller bubble till sizes are interchanged
air flows from smaller bubble to bigger
there is no flow of air
The thermo emf of a hypothetical thermocouple varies with the temperature θ of hot junction as E = in volts, where the ratio is 700o C. If the cold junction is kept at 0o C, then the neutral temperature is
700o C
1400o C
390o C
no neutral temperature is possible for this thermocouple
If the ratio of lengths, radii and Young's modulus of steel and brass wires shown in the figure are a, b Brass and c respectively, the ratio between the increase in lengths of brass and steel wires would
A soap bubble of radius r is blown up to form a bubble of radius 2r under isothermal conditions. If T is the surface tension of soap solution, the energy spent in the blowing
D.
Initially area of soap bubble
Under isothermal condition radius becomes 2 r, Then, area
A2 =
=
Increase in surface area
=
Energy spent
W = T × ΔA
= T . 24
W = 24
A current of 1.6 A is passed through a solution of CuSO4. How many Cu++ ions are liberated in one minute? (Electronic charge= 1.6 x 19-19 C)
3 × 1020
3 × 1010
6 × 1020
6 × 1010
The sound waves after being converted into electrical waves are not transmitted as such because
they travel with the speed of sound
the frequency is not constant
they are heavily absorbed by the atmosphere
the height of antenna has to be increased several times
An engine moving towards a wall with a velocity 50 m/s emits a note of 1.2 kHz. Speed of sound in air is 350 m/s. The frequency of the note after reflection from the wall as heard by the driver of the engine is
2.4 kHz
0.24 kHz
1.6 KHz
1.2 kHz
The surface temperature of the sun which has maximum energy emission at 500 nm is 6000 K. The temperature of a star which has maximum energy emission at 400 nm will be
8500 K
4500 K
7500 k
6500 K
0.1 m2 of water at 80°C is mixed with 0.3 m3 of water at 60°C. The final temperature of the mixture is
65o C
70o C
60o C
75o C
y = 3 sin represents an equation of a progressive wave, where t is in second and x is in metre. The distance travelled by the wave in 5 s is
8 m
10 m
5 m
32 m