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3 years ago

The rate at which work is done is also the definition of which of the following?

Physics

1 answer:

gregori [183]3 years ago

7 0

B) Power
Because Power= Work/time

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In a photoelectric experiment it is found that a stopping potential of 1.00 V is needed to stop all the electrons when incident

kiruha [24]

Answer:

Planck’s constant is $6.9*10^{-34} Js$

work function of metal is $5.846*10^{-19}$

Explanation:

The maximum kinetic energy from electron from photoelectric effect is given by

$\K_{max}=eV_o$ where $V_o$ is applied voltage and e is charge on electron and substituting charge on electron by $1.6*10^{-19}$ and 1.00 V for $V_o$

$K_{max}=1.6*10^{-19}*1=1.6*10^{-19} J$

Considering that the wavelength, \lambda of light used is given as $278*10^{-9} m$

Energy of light is given by

$E=\frac {hc}{ \lambda}$ where $\lambda$ is the wavelength, h is Planck’s constant and c is speed of light. Taking c for $3*10^{8} m/s$

Substituting values of wavelength and speed of light we obtain

$E=\frac {h*3*10^{8}}{278*10^{-9}}=h1.07914*10^{15} J$

If work function is $\phi$ then

$E=\phi + k_{max}$ hence

$h1.07914*10^{15} J=\phi +1.6*10^{-19} J$ ------- Equation 1

Energy corresponding to wavelength of 207 nm is

$E=h\frac {3*10^{8} m/s}{207*10^{-9}}=h(1.45*10^{15}}) J$

Maximum kinetic energy of electrons when $V_o$ is 2.6 V becomes

$K_{max}=(1.6*10^{-19})*2.6V=4.16*10^{-19} J$

From $E=\phi + k_{max}$ and substituting $h(1.45*10^{15}}) J$ for E and $4.16*10^{-19} J$ for $K_{max}$ we have

$h(1.45*10^{15}}) J=\phi +4.16*10^{-19} J$ ------ Equation 2

Equation 2 minus equation 1 gives

$h3.71*10^{14}=2.56*10^{-19}$

$h=\frac {2.56*10^{-19}}{3.71*10^{14}}\approx 6.9*10^{-34} Js$

Therefore, Planck’s constant is $6.9*10^{-34} Js$

Recalling equation 1 and substituting back the value of h as obtained

$h1.07914*10^{15} J=\phi +1.6*10^{-19} J$

$(6.9*10^{-34})*(1.07914*10^{15})=\phi +1.6*10^{-19} J$

$\ph=(6.9*10^{-34})*(1.07914*10^{15})-(1.6*10^{-19})=5.846*10^{-19}$

Therefore, work function of metal is $5.846*10^{-19}$

5 0

3 years ago

Why does the weight of water pulls the central part of the surface down?

Brut [27]

Answer:

Buoyancy or Upthrust

Explanation:

This is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object.

5 0

3 years ago

What is Power can be define as

Ksju [112]

Power (physics) In physics, power is the rate of doing work, the amount of energy transferred per unit time. In the International System of Units, the unit of power is the joule per second (J/s), known as the watt in honour of James Watt, the eighteenth-century developer of the steam engine condenser.

5 0

3 years ago

Determine the stopping distances for a car with an initial speed of 88 km/h and human reaction time of 2.0 s for the following a

seropon [69]

Explanation:

Given that,

Initial speed of the car, u = 88 km/h = 24.44 m/s

Reaction time, t = 2 s

Distance covered during this time, $d=24.44\times 2=48.88\ m$