class 10 physical science model activity task 2021 part 6 solution september 2021#Madhyamiknewsray

 

2.1: Potassium orosyanide K [Au (CN)]

2.2: Kilowatt (kW)

2.3 : One of the practical advantages of AC over DC is -

Very low energy loss and very low cost substitute (AC) can be transmitted to a very remote place.

3.1 : If the thumb, middle finger and index finger of the left hand are extended at right angles to each other, if the index finger points in the direction of the magnetic field and the middle finger points in the direction of electric current, then the thumb will point in the direction of motion.

3.2 : CaCO₃                 = CaO + CO₂⬆

40 + 12 + (16 ｘ3)                     12 + (16 ｘ2)

=40 + 12 + 48                             = 12 + 32

= 100g                                           = 44g

So, 50g                                         = 22g

Ans: In case of first wire, Cross-sectional area (A₁) = πr₁²

In case of second wire, Cross-sectional area (A₂) = πr₂²

In the first condition, l₁: l₂ = 2: 1  ஃ l₁ / l₂ = 2/1

In the second condition, r₁: r₂ = 1: 2 Or, r₁ / r₂ = 1/2 ஃ r₂ / r₁ = 2/1

In the third condition, P₁: P₂ = 3: 4 ஃ P₁: P₂ = 3/4

We know, R = P.l / A

ஃ First wire resistance, R₁ = P₁.l₁ / A₁ --------- (i)

ஃ Second wire resistance, R₂ = P₂.l₂ / A₂ --------- (ii)

Now we get (i) ➗ (ii),

Or, R₁ / R₂ = P₁.l₁ / A₁ / P₂.l₂ / A₂

Or, R₁ / R₂ = P₁.l₁ / A₁ ｘA₂ / P₂.l₂

Or, R₁ / R₂ = P₁.l₁.πr₂² / πr₁².P₂.l₂

Or, R₁ / R₂ = (P₁ / P₂) (l₁ / l₂) (r₁ / r₂)

Or, R₁ / R₂ = (3/4) (2/1) (2/1)

Or, R₁ / R₂ = 6/1

Or, R₁: R₂ = 6: 1