The probability of finding a green signal on a busy crossing X is 30 % . What is the probability of finding a green signal on X on two consecutive days out of three?

Let A be the event of finding a green signal on a busy crossing X The probability of finding a green signal on a busy crossing X is 30 % . P A = 30 100 = 3 10 The probability of not finding a green signal on a busy crossing X is P A ¯ = 1 - 3 10 = 7 10 . The probability of finding a green signal on X on two consecutive days out of three = P A P A P A ¯ + P A ¯ P A P A = 3 10 × 3 10 × 7 10 + 7 10 × 3 10 × 3 10 = 63 500 .

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Important Questions on Current Electricity

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In Balmer series for hydrogen atom, find the energy of photon corresponding to longest wavelength.

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A die marked

1, 2, 3

in red

4, 5, 6

in green tossed. Let

A

be the event "number is even" and

B

be the event "number is marked red". Find whether the events

A

and

B

are independent or not.

EASY

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Given the value of Rydberg constant is

10^{7} m^{- 1}

, the wave number of the last line of the Balmer series in hydrogen spectrum will be:

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Explain the role of the ‘first trophic level’ in an ecosystem.

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The electron in a hydrogen atom passes from

n = 4

energy level to

n = 1

energy level. What is the maximum number of photons that can be emitted?

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Physics>Electricity and Magnetism>Current Electricity>Electric Current

The probability of finding a green signal on a busy crossing

X

30 %

. What is the probability of finding a green signal on

X

on two consecutive days out of three?

EASY

Physics>Electricity and Magnetism>Current Electricity>Electric Current

If 20J of energy is trapped at producer level, then how much energy will be available to peacock as food in the following chain?
plant

\to

mice

\to

snake

\to

peacock

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The ratio of wavelengths of the last line of the Balmer series and the last line of the Lyman series is_____.

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A problem in mathematics is given to three students

A, B, C

and their respective probability of solving the problem is

\frac{1}{2}, \frac{1}{3}

and

\frac{1}{4}

, the probability that the problem will be solved is

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Physics>Electricity and Magnetism>Current Electricity>Electric Current

An electron from various excited states of hydrogen atom emit radiation to come to the ground state. Let

λ_{n}, λ_{g}

be the de Broglie wavelength of the electron in the

n^{t h}

state and the ground state respectively. Let

\land_{n}

be the wavelength of the emitted photon in the transition from the

n^{t h}

state to the ground state. For large n, (A, B are constants)

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Give a diagrammatic representation of energy flow through different trophic levels.

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Four persons can hit a target correctly with probabilities

\frac{1}{2}, \frac{1}{3}, \frac{1}{4}

and

\frac{1}{8}

respectively. If all hit at the target independently, then the probability that the target would be hit, is

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A $10 V$ cell of negligible internal resistance is connected in parallel across a battery of emf $200 V$ and internal resistance $38 Ω$ as shown in the figure. Find the value of current in the circuit.

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The wire with light blue color covering is live wire while brown color covering is neutral wire.

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Important Questions on Current Electricity

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