An electric heater is rated 1500 W. How much energy does it use in 10 hours?
Solution and Explanation
Electric heater’s power \(p = 1500\ W = 1.5\ kW\)
Energy = power × time
Energy = \(1.5\ kW × 10\ h \)
Energy = \(15\ kWh\)
Top Questions on Energy
- Match List-I with List-II:
- During the process of conversion from liquid to solid, the internal energy of the water
- In terms of total primary energy consumption. At present India stands at what position?
- A white dwarf star has volume V and contains N electrons so that the density of electron is \(n=\frac{N}{V}\). Taking the temperature of the star to be 0 K, what will be the expression for average energy per electron in the star?
- The correct statements are:
A. Energy payback time (EPBT) should be less than life of PV System
B. Life cycle conversion efficiency (LCCE) should be less than one
C. Energy production factor (CEPF) on life time basis should be more than one
D. Carbon emission is more if electrical power is generated by PV in comparision to the electrical power generated by conventional power plant
Choose the correct answer from the options given below:
Questions Asked in CBSE Class IX exam
- Explain what the reasons for the following are.
(i) Einstein leaving the school in Munich for good.
(ii) Einstein wanting to study in Switzerland rather than in Munich.
(iii) Einstein seeing in Mileva an ally.
(iv) What do these tell you about Einstein?- CBSE Class IX
- A truly beautiful mind
- (i) The kind of person the doctor is (money, possessions)
(ii) The kind of person he wants to be (appearance, ambition)- CBSE Class IX
- The snake and the mirror
In Fig. 9.26, A, B, C and D are four points on a circle. AC and BD intersect at a point E such that ∠ BEC = 130° and ∠ ECD = 20°. Find ∠ BAC.
- CBSE Class IX
- Angle Subtended by an Arc of a Circle
- Name the two temples the author visited in Kathmandu.
- CBSE Class IX
- Kathmandu
Look up the dictionary entries for the words sympathy, familiarity, comfort, care, and surprise. Use the information given in the dictionary and complete the table.
Noun, Adjective, Adverb, Verb, Meaning:
sympathy
familiarity
comfort
care
surprise- CBSE Class IX
- If I were you
Concepts Used:
Work-Energy Theorem
The work and kinetic energy principle (also known as the work-energy theorem) asserts that the work done by all forces acting on a particle equals the change in the particle's kinetic energy. By defining the work of the torque and rotational kinetic energy, this definition can be extended to rigid bodies.
The change in kinetic energy KE is equal to the work W done by the net force on a particle is given by,
W = ΔKE = ½ mv2f − ½ mv2i
Where,
vi → Speeds of the particle before the application of force
vf → Speeds of the particle after the application of force
m → Particle’s mass
Note: Energy and Momentum are related by, E = p2 / 2m.