A thermal tap used in contain apparatus consist of a silica
rod, which fits inside at
aluminium tube whose internal
diameter is 8 mm out 0°c.
When the temperature is raised the
fit is no longer exact. Calculate
What change in temperature is necessary
to produce a channel whose cross-
Section is equal to that of a
tube of 1 mm internal
diameter.
Linear expansivity of stica = 8x10^-4 k^-1
Linear expansivity of Aluminium = 26x10^-4 k^-1

Suppose that an electromagnetic wave which is linearly polarized along the x−axis is propagating in vacuum along the z−axis. the wave is incident on a conductor which is placed at z > 0 region of the space. the conductor has conductivity σ, magnetic permeability µ and electric permittivity ε. (a) find the characteristic time for the free charge density which dissipates at the conductor. (b) write the maxwell equations and derive the wave equation for a plane wave propagating in a conductor. (c) find the attenuation distance at which the incident amplitude reduces to e ^−1 of its initial value. (d) find the electric and magnetic fields inside the conductor. 8 (e) find the power loss per area of the incident electromagnetic wave at the surface of conductor.

The image shows a pendulum in simple harmonic motion the pendulum starts at a and swing to e

Awave travels at a speed of 5.2 m/s. if the distance between crests is 0.40 m, what is the frequency of the wave? use f=v/wavelength a. 13 hz b. 2.1 hz c. 0.077 hz d. 5.6 hz