A short circuit occurs when a path of very low resistance is created across a voltage source. According to Ohm's Law (I = V/R), as the resistance R approaches zero, the current I increases to a very high, potentially dangerous value, often causing damage to components.

According to Ohm's Law, the potential difference (V) across a component is the product of the current (I) and the resistance (R). Given I = 20 mA = 0.02 A and R = 100 ohms, the calculation is V = 0.02 A * 100 ohms = 2 volts. This confirms the voltage drop across the galvanometer under the specified current conditions.

Electrical conductivity is defined as the reciprocal of electrical resistivity. It measures a material's ability to conduct an electric current. If resistivity is denoted by rho, then conductivity sigma is equal to 1/rho, typically measured in Siemens per meter.

In a parallel circuit, every branch is connected directly across the same voltage source, ensuring that each appliance receives the same potential difference. This allows appliances to operate independently at their rated voltage. While the voltage remains constant, the current drawn by each appliance varies based on its individual resistance, ensuring efficient power distribution across the entire system.

Electrical resistance is the measure of the opposition to current flow in an electrical circuit. It is measured in ohms. Materials with high resistance impede the flow of electrons, while conductors have low resistance. This property is fundamental to Ohm's Law, which relates voltage, current, and resistance in a circuit.

Using Ohm's Law (I = V/R), we convert the voltage to volts (100 mV = 0.1 V) and divide by the resistance (50 Ω). The calculation 0.1 V / 50 Ω equals 0.002 A. Converting this to milliamperes, we get 2.0 mA. This value represents the maximum current the galvanometer can handle before reaching its full-scale deflection limit.

For resistors connected in parallel, the equivalent resistance (Req) is calculated as 1/Req = 1/R1 + 1/R2 + 1/R3. Here, 1/Req = 1/6 + 1/6 + 1/6 = 3/6 = 1/2. Thus, Req = 2Ω.

According to Ohm's Law, the current (I) in a circuit is determined by the ratio of the potential difference (V) to the resistance (R), expressed as I = V/R. Given V = 60V and R = 30Ω, the calculation I = 60 / 30 results in a current of 2A.

According to Ohm's Law, I = V/R. If R becomes R/2, the new current I' = V / (R/2) = 2 * (V/R) = 2I. Therefore, the current is doubled when resistance is halved.

Electrical conductivity is defined as the reciprocal of electrical resistivity. It measures a material's ability to conduct an electric current. While resistivity quantifies how strongly a material opposes the flow of current, conductivity quantifies how easily current can flow through the material, typically measured in Siemens per meter.