Physics
Question from maharashtra board physics book of 12th maharashtra board
- Why should not the jockey be slided along the potentiometer wire? Sliding the jockey on the potentiometer wire decreases the cross sectional area of the wire and thereby affects the fall of potential along... 1
- Are Kirchhoff’s laws applicable for both AC and DC currents? Kirchhoff’s laws are applicable to both AC and DC ’ circuits (networks). For AC circuits with different loads, (e.g. a combination of a resi... 1
- On what factors does the potential gradient of the wire depend? The potential gradient depends upon the potential difference between the ends of the wire and the length of the wire. 1
- Why is potentiometer preferred over a voltmeter for measuring emf? A voltmeter should ideally have an infinite resistance so that it does not draw any current from the circuit. However a voltmeter cannot be... 1
- State the uses of a potentiometer. The applications (uses) of the potentiometer : Voltage divider : The potentiometer can be used as a voltage divider to change the output vol... 1
- What are the disadvantages of a potentiometer? Disadvantages of a potentiometer over a voltmeter : The use of a potentiometer is an indirect measurement method while a voltmeter is a dire... 1
- Distinguish between a potentiometer and a voltmeter. PotentiometerVoltmeter 1. A potentiometer is used to determine the emf of a cell, potential difference and internal resistance.1. A voltmete... 1
- On what factors does the internal resistance of a cell depend? The internal resistance of a cell depends on : Nature of the electrolyte : The greater the conductivity of the electrolyte, the lower is the... 1
- A voltmeter has a resistance 30 Ω. What will be its reading, when it is connected across a cell of emf Data: E = 2V, r = 10 Ω, R = 30 Ω The voltmeter reading, V = IR = ( E/R+r ) R = ( 2/30+10 ) 30 = ( 2/40 ) 30 = 1.5 V 1
- When two cells of emfs. E1 and E2 are connected in series so as to assist each other, their balancing length Data : l₁ = 2.7m (cells assisting), l₂ = 0.3 m (cells opposing) E₁ + E₂ = Kl₁ and E₁ – E₂ = Kl₂ ∴ fracE₁+E₂E₁-E₂=fracK l₁K l₂ ∴ fracE₁E₂=fra... 1
- The emf of a cell is balanced by a length of 120 cm of potentiometer wire. When the cell is shunted by a resistance Data :R = 10 Ω, l₁ = 120 cm, l₂ = 120 – 20 = 100 cm r = R( fracl₁-l₂l₂ ) = 10 ( 120-100/100 ) = 2 Ω The internal resistance of the cell is 2... 1
- A potential drop per unit length along a wire is 5 × 10-3 V/m. If the emf of a cell balances against Data: K = 5 × 10⁻³ V/m , L = 216 cm = 216 × 10⁻² m E = KL ∴ E = 5 × 10⁻³ × 216 × 10⁻² = 1080 × 10⁻⁵ = 0.01080V The emf of the cell is 0.0108... 1
- The resistance of a potentiometer wire is 8 Ω and its length is 8 m. A resistance box and a 2 V Data: R = 8 Ω, L = 8 m, E = 2 V, K = 1 µV/mm = 1 × frac10⁻⁶ ~V10⁻³ ~m = 10⁻³ V/m K = V/L=fracE R(R+R_B) L^(prime) where R_B is the resistanc... 1
- Find the equivalent resistance between the terminals F and B in the network shown in the figure below given Applying Kirchhoff’s voltage law to loop FGHF, we get, – 10I1 – 10(I1 – I2) + 10(I – I1) + 10(I – I1) = 0 ∴ – 10I1 – 10I1 + 10I2 + 10I – 10I... 1
- A voltmeter has a resistance of 100 Ω. What will be its reading when it is connected across a cell of emf 2 V Data: E = 2V, r = 20 Ω, R = 100 Ω The voltmeter reading, V = IR V = ( 2/100+20 )100 = 200/120=10/6 = 1.667 V. 1
- A parallel plate capacitor is charged and then isolated. The effect of increasing the plate separation on charge Answer: (D) Constant, increases, decreases Charge: the capacitor is isolated after charging, so the charge has nowhere to go. Q stays consta... 1
- Energy stored in a capacitor and dissipated during charging a capacitor bear a ratio. (A) 1 : 1 Energy stored in a capacitor and dissipated during charging a capacitor bear a ratio 1 : 1 1
- A parallel plate capacitor has circular plates of radius 8 cm and plate separation 1mm. (A) 1.78 × 10⁻⁸ C 2
- If the difference between the radii of the two spheres of a spherical capacitor is increased The capacitance of a spherical capacitor is C = 4πε₀ (a b/b-a) where a and b are the radii of the concentric inner and outer conducting shel... 1
- A metal plate is introduced between the plates of a charged parallel plate capacitor. Suppose the parallel-plate capacitor has capacitance C₀, plates of area A and separation d. Assume the metal sheet introduced has the same a... 1
- The safest way to protect yourself from lightening is to be inside a car. Justify. There is danger of lightning strikes during a thunderstorm. Because trees are taller than people and therefore closer to the clouds above, t... 1
- A capacitor has some dielectric between its plates and the capacitor is connected to a DC source. Assume a parallel-plate capacitor, of plate area A and plate separation d is filled with a dielectric of relative permittivity (dielectric c... 1
- Two charges of magnitudes -4Q and +2Q are located at points (2a, 0) and (5a, 0) respectively. The sphere of radius 4a encloses only the negative charge Q₁ = -4Q. The positive charge Q₂ = +2Q being located at a distance of 5a from the... 1
- A 6 µF capacitor is charged by a 300 V supply. It is then disconnected from the supply and is connected Data: C = 6 µF = 6 × 10⁻⁶ F = C₁, V = 300 V C₂ = 3 µF The electrostatic energy in the capacitor = 1/2 Cv² = 1/2 (6 × 10⁻⁶)(300)² = 3 × 10⁻⁶... 1