Kirchhoff S Laws

Step 1: Concept
An ammeter is connected in series to measure current.
Step 2: Analysis
To ensure it does not change the circuit's total resistance and the current it aims to measure, it must have no resistance of its own.
Step 3: Conclusion
The resistance of an ideal ammeter is zero.
Final Answer: (A)

Step 1: Concept
Voltage in a closed mesh is given by .
Step 2: Analysis
Given , , and . .
Step 3: Conclusion
.
Final Answer: (C)

Step 1: Configuration
Potassium ( ): .
Step 2: Valence Electron
The outermost (valence) electron is in the orbital ( ).
Step 3: Quantum Numbers
- Principal ( ) = 4
- Azimuthal ( ) for -orbital = 0
- Magnetic ( ) = 0
- Spin ( ) = or .
Step 4: Conclusion
The correct set is .
Final Answer: (c)

Step 1: Thermodynamics Formula
Use the Gibbs free energy equation: .
Step 2: Equilibrium Condition
At 373 K and 1 atm, water and steam are in equilibrium. For any system at equilibrium, .
Step 3: Result
Substituting into the equation gives , which rearranges to .
Final Answer: (c)

Step 1: Calculation
Total resistance . Total current . Current in each branch is .
Step 2: Node Potentials
. .
Step 3: Final Step
Subtracting the equations gives .
Final Answer: (B)

Step 1: Use the formula for the number of ions.
The number of ions liberated can be calculated using the relation: where: - is the total charge passed through the solution, - is the charge of one ion.

Step 2: Calculate the total charge.
The current is passed for . The total charge is:

Step 3: Calculate the number of ions.
Now, using the formula for the number of ions:

Step 4: Conclusion.
The number of ions liberated in one minute is , which is option (1).

Step 1: Understanding the Concept:
Rate of ice formation follows , so .
Step 2: Detailed Explanation:
For first 1 cm: min.
For thickness from 0 to 2 cm: min.
Time to go from 1 cm to 2 cm = min.
Since 36 min 24 min, the time is more than 24 min.
Step 3: Final Answer:
Thus, time is more than 24 min.

Concept: Balanced Wheatstone bridge no current through voltmeter.

Step 1: Check balance
Not balanced.

Step 2: Equivalent circuit
Top branch:
Bottom branch: Parallel combination:

Step 3: Total current
Each branch gets equal current

Step 4: Voltage at midpoint
Top midpoint: Bottom midpoint: Difference: Conclusion:

Concept: Heat produced:

Step 1: Substitute values.

Concept:

Step 1: Rearrange.


Step 2: Substitute values.

Concept: When wire is stretched, volume remains constant:

Step 1: New dimensions.


Step 2: New resistance.

Concept: Use Kirchhoff’s laws and symmetry of network.

Step 1: Identify branches.
Two paths from Q to S:
• Upper:
• Lower:

Step 2: Current division.
Total current = 2A:

Step 3: Potential difference.
From Q → P: From Q → R:

Step 4: Final result.

Concept: Resistance varies linearly with temperature:

Step 1:Substitute values.


Step 2:Solve.

Concept:

Step 1:Let required heat = For first coil: For second coil:

Step 2:Total power (parallel):

Step 3:Time taken:

Step 4:Convert to seconds: