<h2>
a) Equivalent resistance is 143 Ω</h2><h2>
b) Potential difference is 71.5 V</h2>
Explanation:
When resistors are connected in series, effective resistance is given by

Here
R₁ = 21Ω
R₂ = 58Ω
R₃ = 64Ω
a) 
Equivalent resistance is 143 Ω
b) We know
Potential difference = Current x Resistance
V = IR
I = 0.5 A
R = 143Ω
Substituting
V = 0.5 x 143 = 71.5 V
Potential difference is 71.5 V
The charged particles are often deflated in a magnetic field.
<h3>What is a magnetic field?</h3>
The term charge refers to a positive or negative entity. The can be created when a charge is made to pass through a conductor in a magnetic field.
A magnetic field is created when we have a north pole and a south pole. The charged particles could be made to pass through the electric field and when that happens, we can see a pattern a shown in the image attached.
Thus, we can see that the charged particles are often deflated in a magnetic field.
Learn more about magnetic field:brainly.com/question/23096032
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Answer:
momentum=mass×velocity
momentum =400kg×20m/s=8000kg.m/s