Im doing some hw problems and I cannot figure out how to do these for the life of me. Any help would be appreciated. 1. An airplane is flying through a thundercould at a height of 2000 m. If there is a charge concentration of +40 C at 3000 , within the cloud and -40 C at height 1000 m, what is the electric field at the aircraft? 2. Two point charges of values +3.4 and +6.6 C are seperated by .10 m. What is the electrical potential at the point midway between the two point charges? 3. If a lamp has resistance of 120 Ohms when it operates at 100W, what is the applied voltage? 4. The temperature coefficient of resistivity for a "perfect" ohmic material would be?