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Class 12th Magnetism and Matter

Statement I : The ferromagnetic property depends on temperature. At high temperature, ferromagnet becomes paramagnet.

Statement II : At high temperature, the domain wall are of a ferromagnetic substance increases.

In the light of the above statements, choose the most appropriate answer from the options given below:

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Vishal Baghel

Contributor-Level 10

I : at high temperature, ferromagnet becomes paramagnet.

II : at high temperature, domains of ferromagnet will break

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Class 12th Quantitative Aptitude Prep Tips for MBA

Find two numbers such that sum of six times the first and five times the second is 218, and the excess of five times the first over three times the second is 24.

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Raj Pandey

Contributor-Level 9

6X + 5Y = 218 . (1)

5X - 3Y = 24 . (2)

Solve to get X = 18, Y = 22.

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Class 12th Maths

Let a vector $\vec{a}$ be coplanar with vectors $\vec{b} = 2 \hat{i} + \hat{j} + \hat{k} a n d \vec{c} = \hat{i} - \hat{j} + \hat{k} . I f \vec{a}$ is perpendicular to $\vec{d} = 3 \hat{i} + 2 \hat{j} + 6 \hat{k} a n d | \vec{a} | = \sqrt[]{10 .}$ Then a possible value of $[\vec{a} \vec{b} \vec{c}] + [\vec{a} \vec{b} \vec{d}] + [\vec{a} \vec{c} \vec{d}]$ is equal to:

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alok kumar singh

Contributor-Level 10

$\vec{a} = α \vec{b} + β \vec{c} = (2 α + β) i + (α - β) J + (α + β) k$

is perpendicular to $\vec{d} = 3 \hat{i} + 2 \hat{j} + 6 \hat{k}$

$\Rightarrow 3 (2 α + β) + 2 (α + β) + 6 (α + β) = 0$

->14a + 7b = 0 Þ b = -2a .(i)

$\Rightarrow \vec{a} = 3 α j - α k$

$| \vec{a} | = \sqrt[]{9 α^{2} + α^{2}} = \sqrt[]{10} \Rightarrow | α | = 1 \Rightarrow α \pm 1, f o r α = 1, \vec{a} = 3 \hat{j} - \hat{k}$

for $α = - 1, \vec{a} = - 3 \hat{j} + \hat{k}$

$\vec{d} * \vec{a} = \pm | \begin{matrix} i & j & k \\ 3 & 2 & 6 \\ 0 & 3 & - 1 \end{matrix} |$

$= \pm 42$

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Class 12th Quantitative Aptitude Prep Tips for MBA

If the price of a commodity increases by 150%, by what percentage should the consumption decrease so that overall expenditure is same as earlier?

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Raj Pandey

Contributor-Level 9

Let x be the required percent.

Using the successive percentage change rule, we have

150 + x + $\frac{150 x}{100}$ $\frac{}{}$ = 0

$\frac{250 x}{100}$ = – 150

x = – 60%

so 60%

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Class 12th Quantitative Aptitude Prep Tips for MBA

How much time will a wheel take in covering 1760 metres with diameter 3.5 metres and speed of 1 rpm?

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Raj Pandey

Contributor-Level 9

Required time t =

$\frac{1760}{2 π r} = \frac{1760}{[2 * (\frac{22}{7}) * \frac{3.5}{2}]} = 160 m i n .$

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Class 12th Maths

Let f : R ® R be defined as

$f (x) = {\begin{matrix} - \frac{4}{3} x^{3} + 2 x^{2} + 3 x, & x > 0 \\ 3 x e^{x}, & x \leq 0 \end{matrix}$

Then f is increasing function in the interval.

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alok kumar singh

Contributor-Level 10

$f (x) = [\begin{array}{l} - \frac{4}{3} x^{3} + 2 x^{2} + 3 x, x > 0 \\ 3 x e^{x}, x \leq 0 \end{array}$

$f' (x) > 0 f o r x < 0 e^{x} (x + 1) > 0 \Rightarrow X > - 1 \Rightarrow x \in (- 1, 0)$

for x > 0 $- 4 x^{2} + 4 x + 3 > 0$

$\Rightarrow x \in (0, \frac{3}{2})$

Again at x = 0 f'(0) = 3 > 0

$∴ f (x) i s i n c r e a s i n g i n (- 1, \frac{3}{2})$

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Class 12th Physics

Consider a situation in which reverse biased current of a particular P – N junction increase when it is exposed to a light of wavelength $\leq$ 621 nm. During this process, enhancement in carrier concentration takes place due to generation of hole – electron pairs. The value of band gap is nearly.

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Vishal Baghel

Contributor-Level 10

$E = \frac{h c}{λ} = \frac{1242 e V - n m}{621 n m} = 2 e V$

minimum 2eV is required to emit.

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Class 12th Physics

In a circuit consisting of a capacitance and a generator with alternating emf E_g = $E_{g_{0}}$ sin $ω t$ , V_C and I_C are the voltage and current. Correct phase diagram for such circuit is: