# HW: What is energy used? What is wattage?

• JerseyGirl
In summary, a camera flash with a capacitor of 850uF and a potential difference of 280V has an energy of 33J and a power of 8500W, with a flash lasting 3.9E-9 seconds. This can be calculated using the equations W=1/2*C*V^2 and P=E/t, where V is the voltage, C is the capacitance, and t is the time. The energy in a capacitor is 1/2 Q^2/C, and the power is given by P=E/t.
JerseyGirl
Cutnell Physics 7th Ed pg 600 # 39

## Homework Statement

A camera flash has a capacitor.
Capacitor has a rating of: 850uF
The potential difference between the places is: 280V

a) Determine Energy used to produce flash.
b)If flash lasts 3.9E-9 S, what is the power or wattage of the flash?

V=C/F
W=VA
A=C/S

## The Attempt at a Solution

a) (280V)(850uF)= 0.238C

b) (0.238 C)/(3.9E-3 S)= 61.03A
W=?

The back of the book has a) =33J b) 8500W
Where did I go wrong?

Energy = 1/2*C*V^2
Power = E/t

## 1. What is energy used for?

Energy is used to power various systems and processes in our daily lives. It is used for transportation, heating and cooling our homes, lighting, and powering electronic devices.

## 2. How is energy converted into usable forms?

Energy can be converted into different forms such as electricity, heat, or kinetic energy. This conversion happens through various processes like burning fuels, using solar panels, or harnessing wind power.

## 3. What is the difference between energy and wattage?

Energy is the ability to do work, while wattage is a measure of the rate at which energy is being used or transferred. In other words, energy is the amount of work that can be done, while wattage is the speed at which that work is being done.

## 4. How is wattage calculated?

Wattage is calculated by multiplying the voltage (in volts) by the current (in amps). This is known as Ohm's law, which states that wattage equals voltage times current.

## 5. How does energy usage impact the environment?

The production and consumption of energy can have a significant impact on the environment. Burning fossil fuels, which are a major source of energy, releases greenhouse gases and contributes to climate change. However, using renewable sources of energy like solar or wind can help reduce our environmental impact.

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