# Homework Help: Charges, Resistance & Electrical Current, Wavelength

1. May 17, 2006

### ranger12

I am having difficulty with three questions, can anyone help me. I would appreciate it.

Here are the questions,

1. If distance between two charges +q and -2q is 6a, what is profile of the line formed by the points of zero potential?

2. A metal bar of length I and resistance R slides with no friction but with ideal electrical contact along supporting rails of negligible resistance perpendicular to the uniform magnetic field B. During time t bars covers a distance d. Resistors R0 and Rx are connected to the rails as shown in the figure. Resistor Rx is such that the power released across segment ab does not depend on the key position. Derive expressions for
a) Resistance Rx
b) Electric current I for open and closed key

3. Two mirrors are placed together as shown in the figure. What is profile of the line an object and its two images lie on? If an object is a source of monochromatic light of wavelength λ, define an expression describing the condition of the first maximum due to two images interference.

I would appreciate it if anyone knows, that they can help me out.

Thank you.

2. May 17, 2006

### Andrew Mason

You will have to show what you have done so far. eg. in ques. 1, give one point where potential is 0 (what does 0 potential mean?).

AM