Intro to Current Practice Problems

During a 30-minute gaming session, an LED screen uses a power supply with a steady current of 5 A. Over this gaming duration, what amount of electric charge flows through the wire?

An electric car draws a current of 15.0 A from its battery. Over the duration of 1 hour, determine the number of electrons that have flowed from the battery to power the car.

An electronics enthusiast designs a custom circuit board and uses a gold wire with a square cross-section measuring 4.0 mm on each side. The wire is capable of conducting a current of 3.0 A. Compute both the current density and the electron drift speed for this wire.

A power transmission cable made of copper consists of three segments with varying radii. Segments A and C have the same radius of 5.0 cm and are thrice that of segment B as shown below. The current passing through segment A is 1000 A. Calculate the current density J in each of these three segments.

You've installed an electric fence around your farm to protect your crops from wildlife. The fence generates a pulse of electric current with a magnitude of 10 kA for 5 μs. How much charge is delivered by the fence during one pulse?

A bicycle owner wants to electroplate the handlebars with 0.4 g of nickel using a solution with singly charged nickel ions. In mA, how much current is needed to complete the electroplating process in 3.0 hours?

In a neuron, sodium (Na+) ions are important for generating action potentials. A 0.35-nm-diameter sodium ion channel carries a current of 2.4 pA. How many sodium ions pass through if the ion channel opens for 1.5 ms?

A portable Bluetooth speaker with a 20 Ah battery can supply a constant current of 2 A for 10 hours before it becomes completely discharged. Determine the amount of charge that leaves the battery when the speaker is used continuously until it runs out of charge.

A Scanning Electron Microscope generates an electron beam that carries a current of 60 μA. The beam scans the surface of a sample, allowing the user to see minute details on the specimen. How many electrons strike the sample every second?

A circuit consists of two wires made of iron and copper, respectively, connected in series as shown below. If the electric field strength is required to be the same in both wires, and the copper wire has a radius of 2.0 mm, determine the radius of the iron wire.

A high-speed train operates with a power supply system that utilizes overhead wires for electrical transmission. The overhead wire has an outer diameter of 4 cm and an inner diameter of 3 cm. The wire carries a current of 1000 A. Calculate the current density in the wire.

To protect an LED strip light with a maximum current draw of 0.7 Amps, a fuse wire made of a material with a melting point at a current density of 250 A/cm² is used. Determine the required radius of this fuse wire.

Electricity is the flow of charges, generally electrons from high potential to low potential. A circuit breaker is rated at 6300 A (1A = 1 C/s). The breaker will trip if this maximum current is sustained for 50 ms. Determine the i) amount of charge that will flow within that time and ii) the number of electrons that flow within that time.

A particle accelerator uses magnetic fields to accelerate a beam of protons for high-energy collisions. In one of the experiments, a small number of protons hit the target, but the majority passed through and hit a beam stopper. The beam stopper measured a charge accumulating at a rate of 1.5 nC/s. If the experiment lasted for 3.0 hours, how many protons have been accumulated in the stopper?

A cylindrical wire has a diameter that changes uniformly from one end to the other. The diameter at the smaller end is 3.0 mm and at the larger end is 5.0 mm. What is the current density (assume uniform) at each end if a current of 3 A enters at the smaller end?

How many electrons pass through a point in a copper wire each second if a current of 2.5 A is flowing through it?

If 1500 K⁺ ions move across a neuron’s membrane in 3.2 μs, and each potassium ion has the same charge as an electron but is positive, what is the current in μA?