An atom absorbs a photon of wavelength 500 nm
Question: An atom absorbs a photon of wavelength $500 \mathrm{~nm}$ and emits another photon of wavelength $700 \mathrm{~nm}$. Find the net energy absorbed by the atom in the process. Solution:...
Read More →Calculate the momentum of a photon of light of wavelength 500 nm.
Question: Calculate the momentum of a photon of light of wavelength $500 \mathrm{~nm}$. Solution:...
Read More →Solve this following
Question: Mark $(\sqrt{)}$ against the correct answer in the following: Let $f(\mathrm{x})=\left\{\begin{array}{r}\mathrm{x} \sin \frac{1}{\mathrm{x}}, \text { if } \mathrm{x} \neq 0 \\ 0, \text { when } \mathrm{x}=0\end{array}\right.$ Then, which of the following is the true statement? A. $f(\mathrm{x})$ is not defined at $x=0$ B. $\lim _{x \rightarrow 0} f(x)$ does not exist C. $f(\mathrm{x})$ is continuous at $\mathrm{x}=0$ D. $f(\mathrm{x})$ is discontinuous at $\mathrm{x}=0$ Solution: $\mat...
Read More →Visible light has wavelengths in the range of 400 nm to 780 nm.
Question: Visible light has wavelengths in the range of $400 \mathrm{~nm}$ to $780 \mathrm{~nm}$. Calculate the range of energy of the photons of visible light. Solution:...
Read More →Figure shows two identical triode tubes connected in parallel.
Question: Figure shows two identical triode tubes connected in parallel. The anodes are connected together, the grids are connected together. Show that the equivalent plate resistance is half of the individual plate resistance, the equivalent mutual conductance is double the individual conductance and the equivalent amplification factor is the same as the individual amplification factor. Solution:...
Read More →The gain factor of an amplifier is increased from 10 to 12
Question: The gain factor of an amplifier is increased from 10 to 12 as the load resistance is changed from $4 \mathrm{k} \Omega$ to $8 \mathrm{k} \Omega$. Calculate (a) the amplification factor and (b) the plate resistance. Solution:...
Read More →A triode has mutual conductance=2.0 millimho and
Question: A triode has mutual conductance $=2.0$ millimho and plate resistance $=20 \mathrm{k} \Omega$. It is desired to amplify a signal by a factor of 30 . What load resistance should be added in the circuit? Solution:...
Read More →The plate current in a triode can be written as
Question: The plate current in a triode can be written as $\mathrm{i}_{\mathrm{p}}=\mathrm{k}\left(\mathrm{V}_{\mathrm{g}}+\frac{\mathrm{V}_{\mathrm{p}}}{\mu}\right)^{3 / 2}$ Show that the mutual conductance is proportional to the cube root of the plate current. Solution:...
Read More →The plate current, plate voltage and grid voltage of
Question: The plate current, plate voltage and grid voltage of a $6 \mathrm{~F} 6$ triode tube are related as $\mathrm{i}_{\mathrm{p}}=41\left(\mathrm{~V}_{\mathrm{p}}+7 \mathrm{~V}_{\mathrm{g}}\right)^{1.41}$ Where $v_{p}$ and $v_{g}$ are in volts and $i_{p}$ in microamperes. The tube is operated at $v_{p}=250 v_{1} v_{g}=-20 v$. Calculate (a) the tube current, (b) the plate resistance, (c) the mutual conductance and (d) the amplification factor. Solution:...
Read More →Solve this following
Question: Mark $(\sqrt{)}$ against the correct answer in the following: The value of $\mathrm{k}$ for which $f(\mathrm{x})=\left\{\begin{array}{c}\frac{\sin 5 \mathrm{x}}{3 \mathrm{x}}, \text { if } \mathrm{x} \neq 0 \\ \mathrm{k}, \text { if } \mathrm{x}=0\end{array}\right.$ is continuous at $\mathrm{x}=0$ is A. $\frac{1}{3}$ B. 0 C. $\frac{3}{5}$ D. $\frac{5}{3}$ Solution:...
Read More →The plate resistance and the amplification factor of
Question: The plate resistance and the amplification factor of a triode are $10 \mathrm{k} \Omega$ and 20 . The tube is operated at plate voltage $250 \mathrm{~V}$ and grid voltage $-7.5 \mathrm{~V}$. The plate current is $10 \mathrm{~mA}$. (a) To what value should the grid voltage be changed so as to increase the plate current to $15 \mathrm{~mA}$ ? (b) To what value should the plate voltage be changed to take the plate current back to $10 \mathrm{~mA}$ ? Solution:...
Read More →Solve this following
Question: Mark $(\sqrt{)}$ against the correct answer in the following: If $y=e^{x}+e^{x+\ldots \infty}$ then $\frac{d y}{d x}=?$ A. $\frac{1}{(1-y)}$ B. $\frac{y}{(1-y)}$ C. $\frac{y}{(y-1)}$ D. none of these Solution:...
Read More →The plate resistance of a triode is 8k Ω and the transconductance is 2.5millimho.
Question: The plate resistance of a triode is $8 \mathrm{k}^{\Omega}$ and the transconductance is $2.5$ millimho. (a) If the plate voltage is increased by $48 \mathrm{~V}$, and the grid voltage is kept constant, what will be the increase in the plate current? (b) With plate voltage kept constant at this increased value, how much should the grid voltage be decreased in order to bring the plate current back to its initial value? Solution:...
Read More →Solve this following
Question: Mark $(\sqrt{)}$ against the correct answer in the following: If $y=\sqrt{\sin x+\sqrt{\sin x+\sqrt{\sin x+}}} \ldots \infty$ then $\frac{d y}{d x}=?$ A. $\frac{\sin x}{(2 y-1)}$ B. $\frac{\cos x}{(y-1)}$ C. $\frac{\cos x}{(2 y-1)}$ D. none of these Solution:...
Read More →Find the values of rp, μ and gm of a triode operating at plate voltage 200V and
Question: Find the values of $r_{p}, \mu$ and $g_{m}$ of a triode operating at plate voltage $200 \mathrm{~V}$ and grid voltage $-6 \mathrm{~V}$. The plate characteristics as shown in figure. Solution:...
Read More →Solve this following
Question: Mark $(\sqrt{)}$ against the correct answer in the following: If $\mathrm{y}=\sqrt{\mathrm{x}+\sqrt{\mathrm{x}+\sqrt{\mathrm{x}+}}} \ldots \infty$ then $\frac{\mathrm{dy}}{\mathrm{dx}}=$ ? A. $\frac{1}{(2 y-1)}$ B. $\frac{1}{\left(y^{2}-1\right)}$ C. $\frac{2 y}{\left(y^{2}-1\right)}$ D. none of these Solution:...
Read More →The dynamic plate resistance of a triode value is
Question: The dynamic plate resistance of a triode value is $10 \mathrm{k}^{\Omega}$. Find the change in the plate current if the plate voltage is changed from $200 \mathrm{~V}$ to $220 \mathrm{~V}$. Solution:...
Read More →Calculate the amplification factor of a triode value
Question: Calculate the amplification factor of a triode value which has plate resistance of $2 \mathrm{k} \Omega$ and trans conductance of 2 millimho. Solution:...
Read More →Solve this following
Question: Mark $(\sqrt{)}$ against the correct answer in the following: If $y=x^{x^{x \ldots x}}$ then $\frac{d y}{d x}=$ ? A. $\frac{y}{x(1-\log x)}$ B. $\frac{y^{2}}{x(1-\log x)}$ C. $\frac{y}{x(1-y \log x)}$ D. none of these Solution:...
Read More →Mark against the correct answer in the following:
Question: Mark $(\sqrt{)}$ against the correct answer in the following: If $\mathrm{x}=\theta(\cos \theta+\sin \theta)$ and $\mathrm{y}=\mathrm{a}(\sin \theta-\theta \cos \theta)$ then $\frac{\mathrm{dy}}{\mathrm{dx}}=?$ A. $\cot \theta$ B. $\tan \theta$ C. $a \cot \theta$ D. $a \tan \theta$ Solution:...
Read More →Solve this following
Question: Mark $(\sqrt{)}$ against the correct answer in the following: If $\mathrm{x}=\mathrm{a} \cos ^{2} \theta, \mathrm{y}=\mathrm{b} \sin ^{2} \theta$ then $\frac{\mathrm{dy}}{\mathrm{dx}}=$ ? A. $\frac{-a}{b}$ B. $\frac{-\mathrm{a}}{\mathrm{b}} \cot \theta$ C. $\frac{-b}{a}$ D. none of these Solution:...
Read More →Solve this following
Question: Mark $(\sqrt{ })$ against the correct answer in the following: If $\mathrm{x}=\mathrm{a} \sec \theta, \mathrm{y}=\mathrm{b} \tan \theta$ then $\frac{\mathrm{dy}}{\mathrm{dx}}=$ ? A. $\frac{b}{a} \sec \theta$ B. $\frac{b}{a} \operatorname{cosec} \theta$ C. $\frac{b}{a} \cot \theta$ D. none of these Solution:...
Read More →Solve this following
Question: Mark $(\sqrt{)})$ against the correct answer in the following: If $x=a t^{2}, y=2 a t$ then $\frac{d y}{d x}=?$ A. $\frac{1}{t}$ B. $\frac{-1}{t^{2}}$ C. $\frac{-2}{t}$ D. none of these Solution:...
Read More →A triode value operates at Vp=225V and Vg= - 0.5V.
Question: A triode value operates at $\mathrm{V}_{\mathrm{p}}=225 \mathrm{~V}$ and $\mathrm{V}_{\mathrm{g}}=-0.5 \mathrm{~V}$. The plate current remains unchanged if the plate voltage is increased to $250 \mathrm{~V}$ and the grid voltage is decreased to $-2.5 \mathrm{~V}$. Calculate the amplification factor. Solution:...
Read More →The power delivered in the plate circuit of a diode is 1.0W
Question: The power delivered in the plate circuit of a diode is $1.0 \mathrm{~W}$ when the plate voltage is $36 \mathrm{~V}$. Find the power delivered if the plate voltage is increased to $49 \mathrm{~V}$. Assume Langmuir-Child equation to hold. Solution:...
Read More →