The velocity selector in in a mass spectrometer consists of a uniform magnetic field oriented at 90 degrees to a uniform electric field so that a charge particle entering the region perpendicular to both fields will experience an electric force and a magnetic force that are oppositely directed. If the uniform magnetic field has a magnitude of 11.9 ~\text{mT}11.9 mT, then calculate the magnitude of the electric field that will cause a proton entering the velocity selector at 25.325.3 km/s to be undeflected. Give your answer in units of kV/m.

The magnitude of the electric field is 0.3011 kV/m

Explanation:

Magnetic force on the charge = qvB

where;

q is the magnitude of the charge

v is the velocity of the proton

B is the strength of the magnetic field

Electric force on the charge = Eq

where;

E is the magnitude of the electric field

q is the magnitude of the charge

Eq = qvB

E = vB

given;

v = 25.3 km/s

B = 11.9 mT

E = 25.3 x 10³ (m/s) x 11.9 x 10⁻³ (T)

E = 301.1 V/m = 0.3011 kV/m

Therefore, the magnitude of the electric field is 0.3011 kV/m

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.