In this example, if the emf of the 4 V battery is increased to 15 V and the rest of the circuit remains the same, what is the potential difference Vab?

In this example, if the emf of the 4 V battery is increased to 15 V and the rest of the circuit remains the same, what is the potential difference Vab?

The image of the circuit has been attached

At 12 emf Vab = 9.5 V

At 15 emf Vab =  12.94 V

Explanation:

Kirchhoff loop rule states that the sum of the currents coming into a junction equals the sum of the currents going out of a junction. That is to say that the sum is equal to zero.

Calculations

The voltage in a circuit can be calculated using the expression;

V= IR .............1

since the Applying Kirchhoff rule to the circuit we have;

Calculating Vab (the voltage across ab) when the emf is 12 v

let us obtain the value of the current flowing across the circuit using equation 1 and Kirchhoff loop rule

+12 - (I x 2) -(I x 3)-(I x 4)-(4)-(I x 7) = 0

I = 8/16 = 0.5 A

calculating the voltage across Vab we have;

Vab = 4V + (I x 7) + (I x 4)

Vab = 4V + (0.5 x 7) + (0.5 x 4)

Vab = 4 +3.5+2

Vab = 9.5 V

at 12v emf Vab is 9.5V

calculating Vab at 15 emf value using equation and also Kirchhoff's loop rule we have;

+15 - (I x 4) -(I x 3)-(I x 2)-(12)-(I x 7) = 0

I = 3/16

I =0.1875 A

Vab = 15 V -(I x 7) - (I x 4)

Vab = 15 - ( 0.1875 x 4)-(0.1875  x 7)

Vab = 15 - 0.75-1.3125

Vab = 12.94 V

15.3 cos 65 degrees trig

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia