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In the equation for instantaneous EMF, $\varepsilon = \varepsilon_0 \sin 2\pi nt$, what does '$n$' represent?
The NCERT text explains, 'Since $\omega = 2\pi n$, Eq (6.20) can be written as $\varepsilon = \varepsilon_0 \sin 2\pi n t$ (6.21) where $n$ is the frequency of revolution of the generator’s coil'.
The polarity of the EMF produced by an AC generator changes periodically. This is because:
The NCERT text states, 'Since the value of the sine function varies between +1 and –1, the sign, or polarity of the emf changes with time.'
Nicola Tesla is credited with the development of which significant aspect related to AC generation?
The NCERT text explicitly states, 'The Yugoslav inventor Nicola Tesla is credited with the development of the machine (AC generator).'
In an AC generator, the mechanical energy required to rotate the armature can be provided by different sources. Which type of generator uses water falling from a height?
The NCERT text states, 'In commercial generators, the mechanical energy required for rotation of the armature is provided by water falling from a height, for example, from dams. These are called hydro-electric generators.'
Which of the following principles forms the basis for the operation of hydraulic lift and hydraulic brakes?
According to the provided text, 'A number of devices, such as hydraulic lift and hydraulic brakes, are based on the Pascal’s law. In these devices, fluids are used for transmitting pressure.'
Pascal's Law states that when external pressure is applied to any part of a fluid contained in a vessel, it is transmitted:
The NCERT text explicitly states, 'whenever external pressure is applied on any part of a fluid contained in a vessel, it is transmitted undiminished and equally in all directions. This is another form of the Pascal’s law.'
In a hydraulic lift, if $F_1$ is the force applied on a piston of cross-section $A_1$, and $F_2$ is the force produced on a larger piston of area $A_2$, the relationship between these forces and areas is given by:
The text explains, 'The pressure $P = F_1/A_1$ is transmitted throughout the liquid to the larger cylinder attached with a larger piston of area $A_2$, which results in an upward force of $P \times A_2$. Therefore, $F_2 = PA_2 = (F_1/A_1)A_2$'. This implies $F_1/A_1 = F_2/A_2$.
What is the mechanical advantage of a hydraulic lift if the area of the larger piston is $A_2$ and the area of the smaller piston is $A_1$?
The NCERT text states that 'the applied force has been increased by a factor of $A_2/A_1$ and this factor is the mechanical advantage of the device.'
A hydraulic lift uses two syringes with diameters of 1.0 cm and 3.0 cm for the smaller and larger pistons, respectively. If a force of 10 N is applied to the smaller piston, what is the force exerted on the larger piston?
From Example 9.5: $F_1 = 10 N$. $D_1 = 1.0 cm$, $D_2 = 3.0 cm$. Areas are proportional to $D^2$. So, $A_2/A_1 = (D_2/D_1)^2 = (3.0/1.0)^2 = 9$. Since $F_2/A_2 = F_1/A_1$, then $F_2 = F_1 (A_2/A_1) = 10 N \times 9 = 90 N$.
In a hydraulic system, if the smaller piston is pushed in through a distance $L_1$, and the larger piston moves out through a distance $L_2$, what is the relationship between their movements and cross-sectional areas ($A_1$ and $A_2$)?
As stated in Example 9.5 (b), 'Water is considered to be perfectly incompressible. Volume covered by the movement of smaller piston inwards is equal to volume moved outwards due to the larger piston.' This means $V_1 = V_2$, or $A_1 L_1 = A_2 L_2$.
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The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.