Home
Class 12
PHYSICS
Assertion To locate null defiection the ...

Assertion To locate null defiection the battery key `(K_(1))` is pressed first and then the galvanom eter key `(K_(2))`
Reason if first `K_(2)` is pressed and then as soon as `K_(1)` is pressed current suddenly try to increase so due to self induction a large stopping emf is generated in galvanometer which may damage the glavanometer .

A

A. if both Asseration and Reason are true and the Reason is a correct explation of Asseration

B

B. if both Asseration and Reason are true and the Reason is a correct explation of Asseration

C

C. if Asseration is ture but Reason is false

D

D. If both Assertion and Reason are false

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question regarding the assertion and reason about the operation of a galvanometer and the keys involved, we can break it down into a step-by-step explanation: ### Step 1: Understand the Assertion The assertion states that to locate the null deflection in a galvanometer, the battery key \( K_1 \) should be pressed first, followed by the galvanometer key \( K_2 \). This means that the battery should be connected to the circuit before the galvanometer is activated. ### Step 2: Understand the Reason The reason provided explains that if the galvanometer key \( K_2 \) is pressed first, and then the battery key \( K_1 \) is pressed, the current will suddenly try to increase. This sudden change in current can induce a large back electromotive force (emf) in the galvanometer due to self-induction, which can potentially damage the galvanometer. ### Step 3: Analyze the Circuit 1. **Circuit Components**: The circuit consists of a battery (with key \( K_1 \)) and a galvanometer (with key \( K_2 \)). 2. **Inductance of the Galvanometer**: The galvanometer has an inductance \( L \), which means it can oppose changes in current due to self-induction. ### Step 4: Explain the Process 1. **Pressing \( K_1 \) First**: When \( K_1 \) is pressed first, the battery is connected, and the circuit is powered. The galvanometer is still open (not connected), so there is no current flowing through it. 2. **Pressing \( K_2 \) Second**: When \( K_2 \) is pressed after \( K_1 \), the galvanometer is connected to the circuit where a steady current is already established. This allows the galvanometer to measure the current without experiencing a sudden change, thus avoiding damage. 3. **If \( K_2 \) is Pressed First**: If \( K_2 \) is pressed first, the galvanometer will initially have zero current. When \( K_1 \) is pressed, the sudden increase in current will induce a back emf in the galvanometer due to its inductance. According to Lenz's law, this back emf will oppose the change in current, causing a significant deflection in the galvanometer pointer, which can lead to damage. ### Step 5: Conclusion Both the assertion and reason are true, and the reason correctly explains why the assertion is necessary. Therefore, the correct conclusion is that pressing \( K_1 \) before \( K_2 \) is essential to prevent damage to the galvanometer. ### Final Answer Both the assertion and reason are true, and the reason is a correct explanation of the assertion. ---
Promotional Banner

Topper's Solved these Questions

  • EXPERIMENTAL PHYSICS

    RESONANCE ENGLISH|Exercise Exercise|12 Videos

  • EXPERIMENTAL PHYSICS

    RESONANCE ENGLISH|Exercise Exercise -1 PART|1 Videos

  • ELECTROSTATICS

    RESONANCE ENGLISH|Exercise HLP|40 Videos

  • GEOMATRICAL OPTICS

    RESONANCE ENGLISH|Exercise Advance level Problems|35 Videos

Similar Questions

Explore conceptually related problems

To locate null point, deflection battery key K_(1) is pressed before the galvanometer key K_(2) . Explain why?

To locate null point deflection battery key (K_1) ios pressed before the galvanometer (K_2) Explanation why?

In the given circuit, calculate the ratio of currents through the battery if (1) Key K_(1) is pressed, K_(2) open and then (2) Key K_(2) is pressed, key K_(1) is opened

In the circuit given in tigure, 1 and 2 are ammeters. Just after key K is pressed to complete the circuit the reading will be

The galvanometer deflection , when key K_(1) is closed but K_(2) is open equals theta_(0) (see figure ) On closing k_(2) also and adjusting R_(2) to 5Omega , the deflection in galvanometer becomes (theta_(0))/(5) the resistnce of the galvanometer is then , given by [Neglect the internal resistance of battery]:

A circuit containing capacitors C_1 and C_2 , shown in the figure is in the steady state with key K_1 and K_2 opened. At the instant t = 0 , K_1 is opened and K_2 is closed. (a) Find the angular frequency of oscillations of L- C circuit. (b) Determine the first instant t , when energy in the inductor becomes one third of that in the capacitor. (c) Calculate the charge on the plates of the capacitor at that instant.

B_(1), B_2 and B_3 are the three identical bulbs connected to a battery of steady emf with key K closed. What happens to the brightness of the bulbs B_(1) and B_(2) when the key is opened?

Two inductors of self inductances L_(1) and L_(2) and of resistances R_(1) and R_(2) (not shown) respectively are conneted in the circuit as shown. At the instant t = 0, key k is closed. Obtain an expression for which the galvanometer will show zero deflection at all times after the key is closed.

Assertion :- The dissocation constant of poly basic acid are in order K_(1)gtK_(2)gtK_(3) . Reason :- The H^(+) ion furnished in first step of dissocation exert common ion effect to reduce the second dissociation and soon.

A thermocol vessel contains 0.5kg of distilled water at 30^(@)C . A metal coil of area 5 xx 10^(-3) m^(2) , number of turns 100 , mass 0.06 kg and resistance 1.6 Omega is lying horizontally at the bottom of the vessel. A uniform time-varying magnetic field is set up to pass vertically through the coil at time t = 0 . The field is first increased from zero to 0.8 T at a constant rate between 0 and 0.2 s and then decreased to zero at the same rate between 0.2 and 0.4s . the cycle is repeated 12000 times. Make sketches of the current through the coil and the power dissipated in the coil as function of time for the first two cycles. Clearly indicate the magnitude of the quantities on the axes. Assumes that no heat is lost to the vessel or the surroundings. Determine the final tempreture of water under thermal equilibrium. Specific heat of metal = 500 j kg^(-1) K^(-1) and the specific heat of water = 4200 j kg^(-1) K^(-1) . Neglect the inductance of coil.