Electric Current

From Joule's law, the heat produced is given by where is potential and the resistance. When one bulb is fused, the total resistance of the circuit decreases.
Hence, illumination increases.

Drift velocity per unit electric field is called mobility of electron,
ie,
Now,

Step 1: Understand the requirements for solar cell materials.
A good solar cell material needs to have high absorption (to absorb as much light as possible), a suitable energy band gap (for efficient conversion of light into electrical energy), and high availability (so that the material can be produced at scale).
Step 2: Identify the incorrect characteristic.
High conductivity is not a desirable property for solar cell materials.
Ideally, the material should have moderate conductivity to allow efficient charge separation without excessive recombination of carriers.

Step 1: Understanding the Purpose of a Shunt
To convert a galvanometer into an ammeter, a shunt resistor is used.
The purpose of the shunt is to allow a large current to bypass the galvanometer, which is typically designed for small currents.
This prevents the galvanometer from being damaged by high currents.
Step 2: Why the Shunt is Connected in Parallel
A shunt resistor is connected in parallel to the galvanometer so that the majority of the current flows through the shunt, leaving only a small portion of the current to pass through the galvanometer.
This allows the galvanometer to measure high currents without being damaged.
Step 3: Conclusion
Thus, a galvanometer is converted into an ammeter by connecting a low resistance shunt in parallel to it.

Step 1: Understand the relationship between current and other quantities.
In a steady current, the amount of charge passing through a cross-section of the conductor per unit time remains constant.
This means the current is the same at all points along the conductor, regardless of its cross-sectional area.
Step 2: Drift speed and current density vary.
Drift speed varies depending on the cross-sectional area of the conductor.

Current density, which is the current per unit area, also varies as the cross-section changes.

Step 1: Understand the concept of resistance in a cell.
In a cell, the opposition to the flow of current within the electrolyte is referred to as the internal resistance.
It is due to the resistance of the electrolyte and the internal parts of the cell.
Step 2: Identify the correct term.
External resistance refers to the resistance outside the cell in the external circuit.
Internal resistance is the term that specifically refers to the opposition inside the cell.