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3 years ago

What is the longest wavelength of light that will emit electrons from a metal whose work function is?

1 answer:

6 0

Best Answer: hf = work function + KE
However if you are looking at the max wavelength (or threshold frequency) then there will only be just enough energy for the photoelectrons to be liberated, hence their KE will be 0.
So hf = work function
convert eV to joules, 2.4 x (1.6 x 10^-19) = 3.84 x 10^-19
therefore, hf = 3.84 x 10^-19
f = 3.84 x 10^-19 / planck's constant which is 6.63 x 10^-34
f = 5.79 x 10^14 Hz
c = frequency x wavelength,
wavelength = speed of light/frequency
= (3x10^8)/(5.79x10^14)
=5.18 x 10^-7 metres

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The temperature of a smelting furnace is found to be 2000 degree Celsius.find the temperature on Fahrenheit scale

Dima020 [189]

Answer:

3632.

Explanation:

Based on the formula:

2000×(9/5)+32=3632

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3 years ago

A 25 kg child is riding on a swing. If the child travels 8.9 m/s at the bottom of their swing, how high into the air is the chil

Setler [38]

Answer:

h = 4.04 m

Explanation:

Given that,

Mass of a child, m = 25 kg

The speed of the child at the bottom of the swing is 8.9 m/s

We need to find the height in the air is the child is able to swing. Let the height is h. Using the conservation of energy such that,

$mgh=\dfrac{1}{2}mv^2\\\\h=\dfrac{v^2}{2g}$

Put all the values,

$h=\dfrac{(8.9)^2}{2\times 9.8}\\\\h=4.04\ m$

So, the child is able to go at a height of 4.04 m.

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3 years ago

What was the result of the Mexican army's victory over the Texan garrison at the Alamo?

sasho [114]

The result of the Mexican victory was that fallen defenders became heroes to the cause of Texan independence. The Battle of the Alamo took place between February 23 and March 6, 1836 and became the central episode of the Texas Revolution . After this thirteen-day battle, the Mexican troops of General President Antonio Lopez de Santa Anna began an attack on San Antonio de Bexar, the current San Antonio in Texas. The Battle of the Alamo fought the army of Mexico against a group of Texan rebels, mostly American settlers. More than four thousand men from Santa Ana stood in front of the Alamo Fort , the last stronghold of the rebels, which barely reached 187. The Alamo was not a fortress prepared to withstand a siege. It is believed that all the rebels of the Alamo died in the siege, but Santa Anna came to lose up to about 900 men during the days that lasted the fight. However, the worst result for Santa Ana was precisely the resistance that the Texan rebels had in the Alamo, which fostered the fighting spirit of the Texans. A few days later, on March 14, 1836, Texas became independent from Mexico and a month later, Santa Ana was imprisoned.

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3 years ago

Read 2 more answers

You measure the power delivered by a battery to be 4.26 W when it is connected in series with two equal resistors. How much powe

gtnhenbr [62]

Answer:

The power delivered by the battery is 17.04 W

Explanation:

Power through a circuit is given as

P = IV ....1

where P is the power

I is the current through the circuit

V is the voltage through the circuit

The voltage in a circuit is given as

V = IR ....2

Let us take the value of each resistor as equal to R

when connected in series, the total resistance will be

$R_{t}$ = R + R = 2R

If we assume constant voltage through the circuit, then from equation 2, the current in this case is

I = V/2R

If the resistors are connected in parallel, then the total resistance will be

$\frac{1}{R_{t} }$ = $\frac{1}{R}$ +

$R_{t}$ = R/2

The current in this case will be increased since the resistance is reduced

I = 2V/R

comparing the two situations, we can see that the current increased when connected in parallel to a ratio of

$\frac{2V}{R}$ ÷ $\frac{V}{2R}$ =

This means that the current increased 4 times

From equation 1, we can see that electrical power is proportional to the current at a constant voltage, therefore, the power will also increase by four times to

P = 4 x 4.26 = 17.04 W

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4 years ago

WHAT IS THE MASS OF AN OBJECT THAT WEIGHS 100 N?

Finger [1]

Answer:

10.2 kg

Explanation:

Assuming the object is on Earth:

w = mg

m = w / g = 100 / 9.81 = 10.2kg

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3 years ago