A straight wire carrying a current of \(12\;A\) is bent into a semi-circular arc of radius \(\text{2.0 cm}\) as shown in Fig.\((a).\) Consider the magnetic field \(B\) at the Centre of the arc. In what way the contribution to \(B\) from the semicircle differs from that of a circular loop and in what way does it resemble?
Answer
For all segments of the semicircular arc, \(\mathit{dl}\times r\) are all parallel to each other \((\)into the plane of the paper\().\) All such contributions add up in magnitude. Hence direction of \(B\) for a semicircular arc is given by the right-hand rule and magnitude is half that of a circular loop. Thus \(B=\frac{\mu_0I}{2R}\) Here, \(R=\) radius \(=2\ cm\ =\ 0.02\ m\) \(I\ =\ \)current \(=\ 12\ A\) \(\mu_0=4\pi\times10^{-7}\ Tm/A\) \(\Rightarrow B=\frac{4\pi\times10^{-7}\times12}{2\times0.02}=1.9\times 10^{-4}\; \text T\) normal to the plane of the paper going into it.
The figure shows an electrolyte of AgCl through which a current is passed. It is observed that \(2.68\;g\) of silver is deposited in \(10\;minutes\) on the cathode. Find the heat developed in the \(20\;\Omega\) resistor during this period. Atomic weight of silver is \(107.09g/mol^{-1}\)
In the following question a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices. (a) Assertion and reason both are correct statements and reason is correct explanation of assertion. (b)Assertion and reason both are wrong statements. (c) Assertion is correct statement but reason is wrong statement. (d) Assertion is wrong statement but reason is correct statement. (e) Assertion and reason both are correct statements but reasson is not correct explanation of assertion. Assertion : The \( \alpha \) -hydrogen atom in carbonyl compounds is less acidic. Reason : The anion formed after the loss of \( \alpha \) -hydrogen atom is resonance stabilised.
A straight wire carrying a current of \(12\;A\) is bent into a semi-circular arc of radius \(2.0\;\mathit{cm}\) as shown in \(\mathit{Fig.}(a).\) Consider the magnetic field \(B\) at the Centre of the arc. Would your answer be different if the wire were bent into a semi-circular arc of the same radius but in the opposite way as shown in \(\mathit{Fig.}(b).\)?
The position of a particle is given by \(r=3.0t\ \hat {i}-2.0t^{2}\ \hat {j}+4.0\ \hat{k}\ m\) where \(t\) is in seconds and the coefficients have the proper units for \(r\) to be in metres. Find the \(\overrightarrow {v}\) and \(\overrightarrow {a}\) of the particle?
Consider a tightly wound \(100\) turn coil of radius \(10 \text{ cm}\) carrying a current of \(1\;A\) . What is the magnitude of the magnetic field at the centre of the coil?
An inductor of inductance \( 100mH\) is connected in series with a resistance, a variable capacitance and an AC source of frequency \( 2.0kHz\). What should be the value of the capacitance so that the maximum current may be drawn into the circuit?
A \(100\) turn closely wound circular coil of radius \(10\;\text{cm}\) carries a current of \(3.2A\). The coil is placed in a vertical plane and is free to rotate about a horizontal axis, which coincides with its diameter. A uniform magnetic field of \(2T\) in the horizontal direction exists such that initially the axis of the coil is in the direction of the field. The coil rotates through an angle of \(90^0\) under the influence of the magnetic field. What are the magnitudes of the torques on the coil in the initial and final position?
Average over a complete one cycle is a null vector.The position of a particle is given by \(r=3.0t\hat {i}-2.0t^{2}\hat {j}+4.0\hat {k} \ m\) , where \(t\) is in seconds and the coefficients have the proper units for \(r\) to be in metres.What is the magnitude and direction of velocity of the particle at \(t=2.0 \ s\) ?
A \(100\) turn closely wound circular coil of radius \(10\;cm\) carries a current of \(3.2 A. (d) \)What is the angular speed acquired by the coil when it has rotated by \(90^0\) ? The moment of inertia of the coil is\( 0.1\;kg m^2\) .