A particle moving along x- axis has acceleration f, at time t, given f = fo (1-t/T), where fo and T are constants. The particle at t =0 and the instant when f = 0, the particle's velocity (vx) is:
foT
foT2/2
foT2
foT2
If the cold junction of a thermocouple is kept at 0o C and the hot junction is kept at To C, then the relation between neutral temperature (Tn) and temperature of inversion (Ti) is:
Tn = 2Ti
Tn = Ti -T
Tn = Ti -T
Nickel shows the ferromagnetic property at room temperature. If the temperature is increased beyond Curie temperature, then it will show:
paramagnetism
anti -ferromagnetism
no magnetic property
no magnetic property
A.
paramagnetism
Nickel exhibits ferromagnetism because of a quantum physical effect called exchange couplingin which the electron spins of one atom interact with those of neighbouring atoms. The result is aligment of the magentic dipole moments of the atoms, inspite of the randomizing tendency of atomic collisions. The presistent aligment is what gives ferromagnetic material their permanent magnetism.
If the temerature of ferromagnetic material is raised above a certain critical value, called the Curie temperature, the exchange coupling ceases to be effective. Most such material then become simply tend to align with an external field but much more weakly, and thermal agitation can now more easily distrupt the alignmet.
A particle executes simple harmonic oscillation with an amplitude a. The period of oscillation is T. The minimum time taken by the particle to travel half of the amplitude from the equilibrium position is:
T/4
T/8
T/12
T/12
The particle executing simple harmonic motion has a kinetic energy Ko cos2 ωt. The maximum values of the potential energy and the toatal energy are respectively:
0 and 2Ko
Ko/2 and K0
Ko and 2Ko
Ko and 2Ko
A mass of 2.0 Kg is put on a flat pan attached to a vertical spring fixed on the ground as shown in the figure. The mass of the spring and the pan is negligible. When pressed slightly and released the mass executes a simple harmonic motion. The spring constant is 200 N/m. What should be the minimum amplitude of the motion, so that the mass gets detached from the pan?
Take g = `10 m/s2
8.0 cm
10.0 cm
any value less than 12.0 cm
any value less than 12.0 cm
A black body is at 727o C. It emits energy at a rate which is proportional to:
(727)2
(1000)4
(1000)2
(1000)2
An engine has an efficiency of 1/6. When the temperature of sink is reduced by 62o C, its efficiency is doubled. The temperature of the source is:
124o C
37o C
62o C
62o C
For a cubic structure which one of the following relations indicating the cell characteristic is correct?