Blog

The electric field strength is 4.80×104  N/C inside a parallel-plate capacitor with a 1.90 mm  spacing. A proton is released from rest at the positive plate. What is the proton’s speed when it reaches the negative plate? (mass of proton = 1.67 x 10-27 kg, charge of an proton = 1.60 x 10-19 C)

How much charge does a 9.0 V battery transfer from the negative to the positive terminal while doing 21 J of work?

Maria owns a small convenience store, and unfortunately very small, shoplifting related losses occur at her store quite frequently (at least once per week). For the past year she has hired a security guard to attempt to minimize the likelihood of shoplifting occurring. However, after her own analysis she believes she is paying too much for the security guard’s services. Instead of paying for risk prevention technique, Maria has made the decision to set aside money each month to pay for these very low severity and rather predictable shoplifting losses. Which method of risk financing is Maria practicing?

A student wants to make a very small particle accelerator using a 7.0 V battery. a) What speed will a proton have after being accelerated from rest through the 7.0  V potential difference? b) What speed will an electron have after being accelerated from rest through the 7.0  V potential difference?

A microwave beam with a wavelength of 1.5 cm has an intensity of 25 W/m2. What is the magnetic field amplitude? (

In proton-beam therapy, a high-energy beam of protons is fired at a tumor.  As  the protons stop in the tumor, their kinetic energy breaks apart the tumor’s DNA, thus killing the tumor cells. For one patient, it is desired to deposit 0.08 J of proton energy in the tumor. To create the proton beam, protons are accelerated from rest through a 1.2×104 kV potential difference. What is the total charge of the protons that must be fired at the tumor? 

The current in a 100 watt lightbulb is 0.80 A. The filament inside the bulb is 0.30 mm in diameter. a) What is the current density of the filament? b) What is the electron current in the filament, in electrons per second?

In the figure shown below, q = -2.8 nC. What is the electric potential at the point indicated with the black dot? Make sure to include units. 

An electric eel develops a 420 V potential difference between its head and tail. The eel can stun a fish or other prey by using this potential difference to drive a 0.80 A current pulse for 1.0 ms.  a) What is the energy delivered by the pulse? b) What is the total charge that flows?

a) How long must a 0.56 mm diameter aluminum wire be to have a 0.44 A current when connected to the terminals of a 1.5 V flashlight battery? (Resistivity of aluminum = 2.8 x 10-8