Units Based Practice

A researcher applies a voltage of 120 V across two parallel plates separated by a distance of 4.0 cm to create a uniform electric field. What is the field’s strength?

A parallel-plate capacitor has a capacitance of 40 μF. It is connected to a 25 V battery until fully charged how much charge does the capacitor hold?

What is the energy of photon with a wavelength of 248 nm in electron volts (eV)?  (Note: Planck’s constant h = 6.6 × 10⁻^34 J·s, c = 3.0 × 10⁸ m/s, and 1 J = 6.24 x 10^18 eV.

A tuning fork produces a sound wave with a frequency of 440 Hz. What is the wavelength of the sound wave if the speed of sound in air is 352 m/s?

Two resistors, R₁ = 6 Ω and R₂ = 12 Ω, are connected in parallel across a 12 V battery. What is the equivalent resistance in the circuit?

A 2,400 W motor lifts a 50 kg crate vertically. Assuming the crate starts at rest on the ground how high will the create be if the motor operates at full power for 10 seconds? 

Implantable cardiac pacemakers deliver precisely timed electrical pulses to maintain heart rhythm in patients with atrioventricular block. The pulse-generating circuit contains a timing capacitor that charges from a lithium battery (3.0 V) and discharges through the lead electrodes when it reaches a threshold voltage. In a modern device, the timing capacitor has a capacitance of 33 μF. Engineers must also account for the resistance of the lead wire, which is modeled as two segments: a proximal segment (R₁ = 150 Ω) and a distal segment (R₂ = 300 Ω) wired in parallel to reduce total impedance at the electrode tip. The total charge delivered per pulse and the voltage across the parallel resistance both affect pacing threshold and patient safety margins.

How much charge is stored on the timing capacitor per cycle?