The Spot Reflecting Galvanometer is a high-precision null-detector designed for measuring extremely low currents ($10^{-9}$ Amperes). By replacing a physical pointer with a reflected beam of light, it eliminates weight and friction, allowing for unmatched sensitivity in scientific research and bridge balancing.
| Feature | Details |
| Measurement Principle | Moving Coil with Mirror Reflection |
| Sensitivity Range | $0.05 \mu A/\text{mm}$ to $0.5 \mu A/\text{mm}$ |
| Scale Type | 150mm - 200mm Translucent Glass (Center Zero) |
| Suspension Method | Taut-Band Ribbon (Friction-Free) |
| Internal Resistance | Standard $100 \Omega$ / $600 \Omega$ (Customizable) |
| Optical Source | 6V Halogen or High-Intensity LED Projection |
| Damping Type | Electromagnetic Damping (Critical Damping) |
| Power Supply | 220V - 240V AC (For the internal lamp) |
Optical "Weightless" Pointer: Uses a sharp, focused light spot (the "Spot") instead of a metal needle. This removes the mass-inertia of a physical pointer, enabling the detection of pulses that standard meters miss.
Internal Optical Path: The light travels an extended distance inside the housing before hitting the scale, which "magnifies" the movement of the coil for higher resolution.
Anti-Parallax Scale: Since the light spot is projected directly onto the frosted glass scale, there is zero gap between the "pointer" and the scale, ensuring error-free readings.
Torsion Ribbon Suspension: The coil is held by a microscopic gold or bronze ribbon. This ensures the meter is highly responsive and returns to "Zero" instantly without sticking.
Rugged Outer Housing: Housed in a heavy-duty, dust-proof metal or high-impact plastic casing to shield the delicate internal optics from ambient light and debris.
Bridge Circuits: Determining the exact null point in Wheatstone, Kelvin, and Carey Foster Bridges.
Potentiometer Experiments: Measuring EMF with extreme precision.
Biophysics & Chemistry: Detecting minute electrical changes in chemical reactions or biological cells.
Standardization: Serving as a reference for low-current calibration in electrical labs.