20.1 Current

Which of the following can be explained on the basis of conservation of charge in a closed circuit consisting of a battery, resistor, and metal wires?

1. The number of electrons leaving the battery will be equal to the number of electrons entering the battery.
2. The number of electrons leaving the battery will be less than the number of electrons entering the battery.
3. The number of protons leaving the…

If 0.625 × 10²⁰ electrons flow through a circuit each second, what is the current in the circuit?

What is the current in milliamperes produced by the solar cells of a pocket calculator through which 4.00 C of charge passes in 4.00 h?

What is the current when a typical static charge of $0 . \text{250} \mu \text{C}$ moves from your finger to a metal doorknob in $1.00 \mu \text{s}$?

A large lightning bolt had a 20,000-A current and moved 30.0 C of charge. What was its duration?

(a) A defibrillator passes 12.0 A of current through the torso of a person for 0.0100 s. How much charge moves? (b) How many electrons pass through the wires connected to the patient? (See figure two problems earlier.)

The batteries of a submerged non-nuclear submarine supply 1000 A at full speed ahead. How long does it take to move Avogadro’s number ($6 . \text{02} \times \text{10}^{\text{23}}$) of electrons at this rate?

A large cyclotron directs a beam of $\text{He}^{++}$ nuclei onto a target with a beam current of 0.250 mA. (a) How many $\text{He}^{++}$ nuclei per second is this? (b) How long does it take for 1.00 C to strike the target? (c) How long before 1.00 mol of $\text{He}^{++}$ nuclei strike the target?

Using the results of the above example on the example, find the drift velocity in a copper wire of twice the diameter and carrying 20.0 A.