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SubjectiveJEE · Physics · Capacitance
Two large parallel conducting plates are 34 mm apart and carry equal but opposite charges on their facing surfaces. An electron placed midway between the plates experiences a force of 3.2×10−16 N. What is the potential difference (in volts) between the plates?
MCQJEE · Physics · Capacitance
A parallel plate capacitor has d=1mm and C=1F with no medium inside will have :-
MCQJEE · Physics · Capacitance
Three long concentric conducting cylindrical shells have radii R, 2R and 22R. Inner and outer shells are connected to each other. The capacitance across middle and inner shells per unit length is:
MCQJEE · Physics · Capacitance
Let C be the capacitance of a capacitor discharging through a resistor R. Suppose t1 is the time taken for the energy stored in the capacitor to reduce to half its initial value and t2 is the time taken for the charge to reduce to one-fourth its initial value. Then the ratio t1/t2 will be :
SubjectiveJEE · Physics · Capacitance
A parallel capacitor is to be designed with a voltage rating 1kV using a material of dielectric constant 3 and dielectric strength about 107Vm−1. For safety we would like the field 'never to exceed say, 10% of the dipole strength. What minimum area of the plats is required to have a capacitance of 50PF?
SubjectiveJEE · Physics · Modern Physics 1
In an experiment on photoelectric effect, the slope of the cut-off voltage versus frequency of incident light is found to be 4.12×10−15 V s. Calculate the value of Planck’s constant.
SubjectiveJEE · Physics · Modern Physics 1
A cooling object was emitting radiations of time varying wavelength λ = 3000 + 40t, where λ is in Å and t is in second is incident on a metal sheet (of work function 2eV) such that the power incident on sheet is constant at 100 watt. This signal is switched on and off for time intervals of 2 minutes and 1 minute respectively. Each time the signal is switched on, λ again starts from fresh value of 3000 Å. If the metal plate is grounded so that it always remains neutral and electron clouding is negligible then find the maximum photocurrent(mA). The photoemission efficiency is 0.01% and remains constant. (Take hc=12400eV-Å)
SubjectiveJEE · Physics · Modern Physics 2
Suppose that the Sun consists entirely of hydrogen atom and releases the energy by the nuclear reaction, 41H⟶4He with 26 MeV of energy released. If the total output power of the Sun is assumed to remain constant at 3.9×1026W, find the time it will take to burn all the hydrogen. Take the mass of the Sun as 1.7×1030kg.
SubjectiveJEE · Chemistry · Electrochemistry
If for the half cell reactions Cu2++e−→Cu+E∘=0.15 V, Cu2++2e−→CuE∘=0.34 V, Calculate E∘ of the half cell reaction Cu++e−→Cu also predict whether Cu+ undergoes disproportionation or not.
SubjectiveJEE · Chemistry · Electrochemistry
Calculate the emf of the cell Pt, H2(1.0 atm) | CH3COOH (0.1M) || NH3(aq, 0.01M) | H2 (1.0 atm), Pt Ka(CH3COOH) = 1.8×10−5, Kb (NH3) = 1.8×10−5.
MCQJEE · Chemistry · Electrochemistry
The thermodynamic efficiency of cell is given by-
MCQJEE · Chemistry · Electrochemistry
Consider the reaction, Cl2(g)+2Br−(aq)→2Cl−(aq)+Br2(g) The emf of the cell when [Cl−]=[Br−]=0.01M and Cl2 gas at 1 atm pressure while Br2(g) at 0.01 atm will be (E∘ for the above reaction is = 0.29 volt) :
SubjectiveJEE · Chemistry · Chemical kinetics
Ammonia and oxygen reacts at higher temperatures as 4NH3(g) + 5O2(g) ⟶ 4NO(g) + 6H2O(g) In an experiment, the concentration of NO increases by 1.08 ×10-2 mol litre-1 in 3 seconds. Calculate. (i) rate of reaction (ii) rate of disappearance of ammonia (iii) rate of formation of water
SubjectiveJEE · Physics · Unit & Dimension, Basic Maths and Vector
A particle is in a unidirectional potential field where the potential energy (U) of a particle depends on the x-coordinate given by Uₓ = k (1 – cos ax) & k and 'a' are constants. Find the physical dimensions of 'a' & k.
MCQJEE · Mathematics · Binomial Theorem Question
If the coefficients of x7 & x8 in the expansion of [2+3x]n are equal, then the value of n is:
JEE · Mathematics · Trigonometric Equation
The number of solutions of the equation sin2x−2cosx+4sinx=4 in the interval [0,5π] is -
Select Only OneJEE · Chemistry · d-Block Compounds
N2(g) + 3H2(g) → 2NH3(g) ; Haber’s process, Mo is used as
Select The CorrectJEE · Chemistry · s-Block Element
Cs+ ions impart violet colour to Bunsen flame. This is due to the fact that the emitted radiations are of -
SubjectiveJEE · Physics · Newton's Laws of motion & Friction
A force F applied to an object of mass m1 produces an acceleration of 3.00 m/s². The same force applied to a second object of mass m2 produces an acceleration of 1.00 m/s². (i) What is the value of the ratio m1/m2? (ii) If m1 and m2 are combined, find their acceleration under the action of the force F.
JEE · Chemistry · Quantum number & Electronic configurations
The total number of neutrons in dipositive zinc ion with mass number 70 is