![A 15 W Electric Shaver Is Used for 3 Minutes. How Much Energy Does It Use [Solved]](https://www.hellomag.co.uk/wp-content/uploads/2025/02/A-15-W-Electric-Shaver-Is-Used-for-3-Minutes.-How-Much-Energy-Does-It-Use-Solved-1.jpg "A 15 W Electric Shaver Is Used for 3 Minutes. How Much Energy Does It Use [Solved]")
Final Answer: 2,700 Joules (J)
A 15 W electric shaver used for 3 minutes transfers 2,700 Joules of energy.
A 15 W Electric Shaver Is Used For 3 Minutes. How Much Energy Does It Use?
To find the energy transferred by any electrical appliance, you use the standard physics formula:
Energy (E) = Power (P) × Time (t)
Step 1: Identify the Power
The power of the shaver is 15 Watts (W). A Watt is defined as one Joule per second.
Step 2: Convert Time to Seconds (The “Trap”)
This is where most students lose marks. The formula requires time to be in seconds, but the question gives it in minutes.
3 minutes × 60 seconds = 180 seconds.
Step 3: Multiply to get the result
Energy = 15W × 180s = 2,700 J.
Physics Tip: If the answer needs to be in Kilojoules (kJ), simply divide by 1,000.
2,700 J = 2.7 kJ.
What Energy Stores are involved?
While the shaver is running, energy is transferred from an Electrical Store to a Kinetic Store (the moving blades). Some energy is also wasted as Thermal Energy (heat) and Sound.
Understanding the Basics of Electrical Energy Consumption
What is Power (Watt) in Electrical Devices?
Power, measured in watts (W), refers to the rate at which an electrical device consumes energy. The higher the wattage, the more electricity the appliance uses per second.
For example:
- 10W LED bulb – Low energy consumption
- 15W electric shaver – Small power usage
- 2000W hairdryer – High energy consumption
FAQs (Frequently Asked Questions)
1. How much electricity does an electric shaver use per year?
If used for 3 minutes daily, a 15W shaver consumes 0.75 Wh per use. Over a year:
0.75 × 365 = 273.75 Wh = 0.27375 kWh
At £0.30 per kWh, the cost is £0.08 (8p per year).
2. Do electric shavers increase electricity bills significantly?
No, electric shavers consume very little power, typically under £0.10 per year for daily use.
3. Is it better to use a rechargeable shaver instead of a plug-in model?
Yes! Rechargeable shavers store energy efficiently and reduce standby power waste.
4. How can I reduce energy consumption while using an electric shaver?
- Use a rechargeable model.
- Unplug when fully charged.
- Use an energy-efficient model.
- Shave efficiently to reduce runtime.
5. Can I use a solar-powered shaver?
Yes, some solar-powered and USB-C shavers are available, which use renewable energy instead of grid electricity.
Home Diagnostics and Technical Standards Specialist at Hello Mag. She provides high-level Expertise in appliance mechanics and scientific pest management, ensuring every guide follows strict safety protocols and manufacturer standards. As a leading Authority on technical home specs, Kanimozhi audits complex data to provide homeowners with the most accurate, verified, and reliable diagnostic solutions available.
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