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These physical changes could be classified based on their energy requirements: endothermic or exothermic. Endothermic reaction need to absorb energy, while exothermic reaction need to release the energy in order to achieve spontaneous reactions.
Exothermic: Condensation, Freezing, Deposition
Endothermic: Sublimation, Evaporation, Melting
Answer:
2.92 m
Explanation:
As we know, frequency × Wavelength = Speed of light
so here frequency of 102.7 MHz can be written as 102.7× 10⁶ Hz..
So Lambda (wavelength) = 3×10⁸/ 102.7 × 10⁶ which gives 2.92 metres or 2.92 × 10¹⁰ Å
I think its B or D, most likely D.
Answer:
i. 6.923 V
ii. The e.m.f. = 22.5 V
Explanation:
i. The given parameters are;
Length of potentiometer = 1 m
The resistance of the potentiometer = 10 Ω
The e. m. f. of the attached cell = 9 V
The current, I flowing in the circuit = e. m. f/(Total resistance)
The current, I flowing in the circuit = 9 V/(10 + 3) = 9/13 A
The potential difference, p.d. across the 1 m potentiometer wire = I × Resistance of the potentiometer wire
The p.d. across the potentiometer wire = 9/13×10 = 90/13 = 6.923 V
ii) Given that the 1 m potentiometer wire has a resistance of 10 Ω, 75 cm which is 0.75 m will have an e.m.f. given by the following relation;
Where:
E = e.m.f. of the balance point cell
= Resistance of 75 cm of potentiometer wire = 0.75×10 = 7.5 Ω
= Resistance of the cell in the circuit = 3 Ω
V = e.m.f. attached cell = 9 V
E = 7.5*3 = 22.5 V
The e.m.f. = 22.5 V
Answer:
1. Friction enables us to walk freely.
2. It helps to support ladder against wall.
3. It becomes possible to transfer one form of energy to another.
4. Objects can be piled up without slipping.
