Eddy currents

An aluminium cylinder rotates as it falls through a uniform magnetic field. Let it be falling in the y direction and the field direction be z. When its axis of rotation is perpendicular to the field direction (along the x axis), it slows down. When it is parallel to the field direction there is no braking. Why?

Method of images.

Consider a point charge +q at a distance d above an infinite grounded conducting plane. (a) Determine the charge density induced on the surface, then integrate to find the total surface charge. (b) Find the force that the point charge exerts on the conductor by considering the force on the induced surface charge densi ...continues

Magnetic and gravitational fields

Is an magnetic field a form of matter? Explain. What about a gravitational field?

Wave

It takes light 20 min to travel from Mars to Earth. How might this affect a conversation between an astronaut on Mars and people on Earth? Explain. Suppose an ultra-powerful telescope were used for visual communication. Would this telescope speed things up? Why?

Lamb waves in a solid plate (part III)

I am still vague on a couple of things. I know that Φ is a scalar field but what exactly is Ψ? See attached file for full problem description.

4 Introductory Electricity Problems

(See attached file for full problem description) --- A small plastic ball of mass 6.39 x 10-3 kg and charge +0.164 C is suspended from an insulating thread and hangs between the plates of a capacitor (see the drawing). The ball is in equilibrium, with the thread making an angle of 30.0° with respect to the vertical. The ar ...continues

4 Electrostatics Problems: Field, force, potential, energy

(See attached file for full problem description) --- A small plastic ball of mass 6.39 x 10-3 kg and charge +0.164 C is suspended from an insulating thread and hangs between the plates of a capacitor (see the drawing). The ball is in equilibrium, with the thread making an angle of 30.0° with respect to the vertical. The ar ...continues

A small plastic ball of mass...

A small plastic ball of mass 6.39 x 10-3 kg and charge +0.164 C is suspended from an insulating thread and hangs between the plates of a capacitor (see the drawing). The ball is in equilibrium, with the thread making an angle of 30.0° with respect to the vertical. The area of each plate is 0.01215 m2. What is the magnitude of ...continues

Charged particle fired at fixed charge.

(See attached file for full problem description with proper symbols) --- A charge of -4.39 C is fixed in place. From a horizontal distance of 0.0132 m, a particle of mass 9.78 x 10-3 kg and charge -8.74 C is fired with an initial speed of 90.4 m/s directly toward the fixed charge. How far does the particle tr ...continues

Electric field near grounded conducting cylinder.

Consider a grounded conducting cylinder of radius, a, in a uniform electric field, E0 in the x direction. Let the cylinder axis be the z-axis. Using the Laplace's equation solution in cylindrical coordinates, find the potential and the induced surface charge.