Physics conceptual questions answer as many as you can correctly....?

Question

#1. A parallel plate capacitor of capacitance C sub zero has plates of area A with separation d between them. When it is connected to a battery of voltage Vsub0, it has charge of magnitude Qsub0 on its plates. The plates are pulled apart to a sepatation 2d while the capacitor remains connected to the battery. After the plates are 2d apart, what is the magnitude of the charge on the plates and the potential difference between them?
#2. A proton with a charge +e is moving with a speed v @ 50degrees to the direction of magnetic field B. The component of the resulting force on the proton is the direction of B is?
#3. In a loop in a closed circuit, the sum of the current entering a junction equals the sum if the currents leaving a junction because??
#4. Two wires of the same material with the same lenght have differenct diameters. Wire A has twice the diameter of wire B. If the resistance of wire B is R, then that is the resistance of wire A?

Answer 1

I'm going to assume you know how to calculate C for parallel plate capacitor. If no - look it up.
1. When the capacitor is still connected to the battery, it can get as much charge from the battery as it can possibly store.
So q=cv, but recalculate c because the distance is now 2d.
2. F =q VxB, = eBsin50
3. Charge HAS to live the junction, it can't accumulate there forever.
4. resistivity is proportional to cross-sectional area squared. Material and length are the same, so we conclude that the resistance is also proportional to a^2. Therefore, the answer is 4R